Plywood tanks

lyman28 · 12/18/2017, 08:00 AM

Hi everyone, last year we finally bought our own house and didn't transfer my tank with me. I now want to get a large tank and have read many threads on the plywood tanks here. Anybody know how many of these tanks are still running. Many of them should be many years old if they have lasted. Any updates on them would be great, or if they fails what was the cause?

der_wille_zur_macht · 12/18/2017, 08:28 AM

I took mine down last year. In a sense it failed but I fixed the issue and ran it afterwards.

I know of a few that have been running for many years (several at 5+ and one that's probably at 10) without issue. None of those folks are on rc these days.

Monsterfishkeepers is probably a good place to check too. Lots of big wood tanks there.

lyman28 · 12/18/2017, 08:39 AM

Well that sucks. I had read all of the builds at one point and time and started rereading them and thinking I want to give it a go. Your tank was beautiful. What was the issue you had with your tank?

der_wille_zur_macht · 12/18/2017, 12:28 PM

I had a pinhole in the epoxy on the eurobrace. I didn't know about the pinhole, the brace had been painted with epoxy instead of bring poured - originally, the brace was supposed to be several inches above the water but at the last minute I raised the overflow box such that the brace was actually underwater. The tiny pinhole caused the brace to slowly delaminate - if I had stuck with the original water depth that probably wouldn't have happened.

At any rate, I lowered the water level, dried it out, laminated it with fiberglass, and went on my merry way.

I took it down last year for reasons totally unrelated to that damage. The tank was still fully functional and honestly would have probably lasted decades if I hadn't taken it down. When done right, a wood tank can be incredibly durable.

Scrubber_steve · 12/18/2017, 02:31 PM

Personally, I don't get plywood tanks.
Cost isn't a reason for building one over a glass tank. They are a lot of mucking around to build; need a lot of bracing - engineering consideration.

One large plywood tank builder I spoke to agreed with me that he would have been better off building his tank out of concrete.

der_wille_zur_macht · 12/18/2017, 04:14 PM

Cost is debatable, it definitely matters whether or not you include your own time, and how experienced you are. I can knock out a glass tank (assuming glass is all prepped, work space is set up, etc) in a few hours. A wood tank is going to be a heck of a lot more time.

Take cost off the table though and I think it depends on your individual criteria. All tanks require proper engineering and bracing, and honestly the time it takes to do that is more a function of the person than the material. You mention "mucking around" as if it's a bad thing. For some of us, the "mucking around" is the whole reason we are in the hobby, we LIKE spending time on DIY projects - we're not DIY'ing because we want the fastest and least effort solution possible.

Wood can be light, which is a consideration in a large tank. You're not going to be able to put a concrete tank in a pickup truck to move it across town. I did that with my 360g tank. Before the glass was glued in, I could manipulate the tank (set it up on end, turn it over) by myself with ease, even when the glass was in. You also get a degree of freedom with wood - there are some shapes/sizes that are easier to do with wood versus other materials. And - as I was a good example - wood is fairly fault-tolerant and easy to repair. Have a seam blow on an acrylic tank and pretty much 100% of the time, it's scrap. Acrylic isn't tolerant of repairs, the material crazes when it's stressed more than once and doesn't take repeated work well. An epoxy lined wood tank is seriously, incredibly durable. I did a test panel before I built my tank, where I poured the epoxy on a scrap panel of plywood to mimic the finished work product. I then took a 22 ounce demolition hammer and wailed on it as hard as I could over and over. There wasn't so much as a chip or crack. Try that with glass, or even acrylic.

I could go on, but honestly I don't think it is even a valid argument, since I don't think there is ever a single "right" answer when this question is presented in a generic, theoretical manner. The only time this discussion makes sense is in the context of a specific person's preferences, tooling, experience, timeframe, and desire. I would never try to talk someone in (or out) of building a wood tank without knowing the whole context.

ca1ore · 12/18/2017, 05:28 PM

A big plywood tank is far cheaper than a comparable glass or acrylic tank. Problem is they look like crap so have to be built in and longevity is debatable. I built one in 1992 and had oozing issues on and off. Broke it down in 1997. Was mynfirstbeffort, so perhaps builder error, but I bought a glass tank in 1988, and only retired it in 2008.

Scrubber_steve · 12/18/2017, 07:23 PM

When I looked into building a plywood tank myself the costs were more than a glass tank.

The cost of quality ply, plus epoxy coatings, etc.
But the big expense was the cost of the single glass panel.

You buy a glass tank from people that purchase full glass sheets at trade price.
But if, for example, you go to the local glass merchant & get a quote for all the glass panels cut to size to make your own glass aquarium, its far more expensive than buying the aquarium ready made..
I found the cost of just the single panel of glass for the front of a plywood aquarium was as expensive as a retail glass aquarium of the same size.

If i was going to make a very large aquarium (not something you would be moving around in the back of a pick up truck, but built on site) where full glass is out of the question I would use concrete panels. The wall thickness will be thinner than a plywood construction with all the necessary bracing, & bowing would simply be something you wouldn't need to be concerned about.

der_wille_zur_macht · 12/18/2017, 07:48 PM

Quote:

Originally Posted by Twinfallz

When I looked into building a plywood tank myself the costs were more than a glass tank.

The cost of quality ply, plus epoxy coatings, etc.
But the big expense was the cost of the single glass panel.

You buy a glass tank from people that purchase full glass sheets at trade price.
But if, for example, you go to the local glass merchant & get a quote for all the glass panels cut to size to make your own glass aquarium, its far more expensive than buying the aquarium ready made..
I found the cost of just the single panel of glass for the front of a plywood aquarium was as expensive as a retail glass aquarium of the same size.

Specifically regarding the glass panels, it sounds like you just needed to shop around more. When I built my tank, I got quotes for the front panel from about $250 to $750, for literally the exact same piece of glass with the same edge finish - just from different shops. Glass vendor prices vary significantly.

I agree with you, good materials are expensive. But it's a basic fact that (typical) wood tanks are cheaper than (typical) glass tanks. I built my wood 360g from about $800 in materials - it was a poured epoxy tank with 3/4 hardwood ply construction. There are people out there building much cheaper wood tanks (I could have saved a few hundred by doing a painted finish instead of a thick poured finish, for example), but I didn't want to cut corners. Materials for a comparable glass tank would have been about $1400, and a custom built glass tank in the same dimensions was going to be about $2500 - $3500 depending on the builder.

I want to say this with all due respect, but you're claiming you've "looked in to" costs associated with building a wood tank. I've actually done it, a few times. I've built glass tanks, too. I don't have a preference for material. If you don't believe me with respect to wood tanks being cheaper, I can go dig out actual receipts for tanks that actually happened, versus conjecture.

That said, I've said this before in many threads and tried to hint at it above, but regardless of the actual cost, I don't think saving money is a good motivator for DIY'ing or choosing a specific method of DIY. This is a hobby, it's supposed to be fun. You should do what you're comfortable with and good at, and you should do what excites you.

lyman28 · 12/18/2017, 10:21 PM

I'm glad to know the issue with the tank was not catastrophic and easly repairable. Sounds like pouring the epoxy mitigates the risk more than brushing it on. I'll have to consider this. When I'm ready to start I won't be able to pour the sides if the tank is assembled. I would like to do a full 8 foot long tank and basement is only 7.5' high. Any idea how mattshacks's tank lasted with all of his seams? Part of me considered doing a 10' long tank but the seam makes me nervous.

I'm looking at the plywood tank because it would be impossible to get at a tank the size I want into my basement. It won't happen.

der_wille_zur_macht · 12/19/2017, 10:57 AM

I haven't had contact with Mattshack since he stopped updating his thread.

Pouring adds an element of foolproofness. It's pretty much impossoble to do 3 or 4 pours, building to 1/8th of an inch or more, and still get a leak. The thickness also helps with durability from an impact perspective.

If you can't accept a smaller tank I'd use glass mat on the walls and build up a good thickness the old fashioned way. I honestly don't like a lot of the wood tanks that aren't poured but I may be biased. Look at the boat building industry, it's common to build a really thick gelcoat finish on a wood or glass boat. Usually these are with polyester which isn't common on wood tanks but you can do the same with thickened epoxy.

McPuff · 12/19/2017, 07:23 PM

Quote:

Originally Posted by lyman28

I'm glad to know the issue with the tank was not catastrophic and easly repairable. Sounds like pouring the epoxy mitigates the risk more than brushing it on. I'll have to consider this. When I'm ready to start I won't be able to pour the sides if the tank is assembled. I would like to do a full 8 foot long tank and basement is only 7.5' high. Any idea how mattshacks's tank lasted with all of his seams? Part of me considered doing a 10' long tank but the seam makes me nervous.

I'm looking at the plywood tank because it would be impossible to get at a tank the size I want into my basement. It won't happen.

Despite the lower ceiling you should still be able to pour the seams. The panels are another story but you'd be able to get the bottom and back obviously. The sides would not be too much work to do the old fashioned way as Wille suggested. There's a really good thread in here for a 500 gallon plywood tank. The guy did a fantastic job and the thing looks amazing (in the Large Tanks forum).

lyman28 · 12/20/2017, 08:26 AM

Only other idea I had would be to pour the epoxy on the panels at same time before the tank was assembled. Do 3-4 pours that way, assemble so you still get the chemical bond. But it would be the epoxy acting like the glue. Screw it all together and then pour the fillets. I have enough clearance to to that on each seam.

der_wille_zur_macht · 12/20/2017, 08:49 AM

I'm sure that would work if you had good joinery. I would probably let the panels cure completely and then use a router to machine the edges perfect, and another pass to remove the epoxy down to bare wood on the seams. Then use urethane (gorilla glue) and screws (predrilled) to assemble. Then pour fillets as you planned.

I guess what I'm saying is that I trust urethane against bare wood more than I trust epoxy against cured epoxy.

lyman28 · 12/20/2017, 01:02 PM

How far in did the epoxy soak into the wood? If I routed the edges to bar wood, would there be enough epoxy soaked in to the panel intself to affect the strength of the gorilla glue?

der_wille_zur_macht · 12/20/2017, 02:00 PM

Depends on the plywood. If you're using a hardwood veneer it'll probably just barely make it into the first core. No veneer, probably not energy though the first core.

If I wasn't on my phone I would draw a diagram. I would route through the first 1/3rd or so of the plywood such that you're forming an open rabbet for the mating panel to sit against. This gives a bigger surface for the glue and also locks in the angle. The screws will hold it tight while the glue cures and the fillet will seal it.

lyman28 · 12/21/2017, 11:56 AM

Ok thanks. Off topic in a way but was wondering if you keeped an urchin with it? I thought I remember reading somewhere that an urchin can chew through the epoxy. Wondering if that is valid or not?

der_wille_zur_macht · 12/21/2017, 12:32 PM

I did not. I've heard people theorize about that but don't know of a single confirmed example.

oldhead · 12/21/2017, 02:47 PM

I've seen a few of the newer plywood tanks using pond armor. It's already black and silicone will stick to it.

d-man · 12/21/2017, 09:43 PM

I built my 860g, 220g sump, stand and canopy ribs for about $2400 total. In the process of taking it down to hopefully sell my house in next 6 months. I will 100% do a whole bother plywood build at my next place.

muttley000 · 01/21/2018, 01:09 PM

I did a 270 gallon sump using the pour method a few years ago and it has, and continues to perform fine. I am planning a basement build taller than the ceiling and hard come the the same conclusion Wille did. Pour the ends, router the rabbets, and assemble in place. Even though I won't be able to tilt it to a perfect 45 on the corner pours, I will still be able to get plenty of fillet contact by going a little deeper.

McPuff · 01/22/2018, 07:34 AM

Quote:

Originally Posted by muttley000

I am planning a basement build taller than the ceiling

Whoa, what?! How big is this tank going to be???? I definitely want to drive down and see this thing.

muttley000 · 01/25/2018, 08:08 PM

Quote:

Originally Posted by McPuff

Whoa, what?! How big is this tank going to be???? I definitely want to drive down and see this thing.

Sorry, not super clear. Taller than my 6 foot Michigan basement when I stand it on end. Looking at 10' X 4' now.

McPuff · 01/26/2018, 01:02 PM

Quote:

Originally Posted by muttley000

Sorry, not super clear. Taller than my 6 foot Michigan basement when I stand it on end. Looking at 10' X 4' now.

Ok, wow! Are you in Toledo? Or actually in Michigan? I'm in Plymouth.

muttley000 · 01/26/2018, 08:18 PM

Quote:

Originally Posted by McPuff

Ok, wow! Are you in Toledo? Or actually in Michigan? I'm in Plymouth.

I am 8 miles south of the Ohio/Michigan line and 16 miles from the Ohio/Indiana line. I hope to do my build summer of 2019

12/18/2017, 08:00 AM	#1
lyman28 Registered Member Join Date: Dec 2010 Posts: 60	Plywood tanks Hi everyone, last year we finally bought our own house and didn't transfer my tank with me. I now want to get a large tank and have read many threads on the plywood tanks here. Anybody know how many of these tanks are still running. Many of them should be many years old if they have lasted. Any updates on them would be great, or if they fails what was the cause?

12/18/2017, 08:28 AM	#2
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	I took mine down last year. In a sense it failed but I fixed the issue and ran it afterwards. I know of a few that have been running for many years (several at 5+ and one that's probably at 10) without issue. None of those folks are on rc these days. Monsterfishkeepers is probably a good place to check too. Lots of big wood tanks there. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

12/18/2017, 12:28 PM	#4
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	I had a pinhole in the epoxy on the eurobrace. I didn't know about the pinhole, the brace had been painted with epoxy instead of bring poured - originally, the brace was supposed to be several inches above the water but at the last minute I raised the overflow box such that the brace was actually underwater. The tiny pinhole caused the brace to slowly delaminate - if I had stuck with the original water depth that probably wouldn't have happened. At any rate, I lowered the water level, dried it out, laminated it with fiberglass, and went on my merry way. I took it down last year for reasons totally unrelated to that damage. The tank was still fully functional and honestly would have probably lasted decades if I hadn't taken it down. When done right, a wood tank can be incredibly durable. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

12/18/2017, 04:14 PM	#6
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	Cost is debatable, it definitely matters whether or not you include your own time, and how experienced you are. I can knock out a glass tank (assuming glass is all prepped, work space is set up, etc) in a few hours. A wood tank is going to be a heck of a lot more time. Take cost off the table though and I think it depends on your individual criteria. All tanks require proper engineering and bracing, and honestly the time it takes to do that is more a function of the person than the material. You mention "mucking around" as if it's a bad thing. For some of us, the "mucking around" is the whole reason we are in the hobby, we LIKE spending time on DIY projects - we're not DIY'ing because we want the fastest and least effort solution possible. Wood can be light, which is a consideration in a large tank. You're not going to be able to put a concrete tank in a pickup truck to move it across town. I did that with my 360g tank. Before the glass was glued in, I could manipulate the tank (set it up on end, turn it over) by myself with ease, even when the glass was in. You also get a degree of freedom with wood - there are some shapes/sizes that are easier to do with wood versus other materials. And - as I was a good example - wood is fairly fault-tolerant and easy to repair. Have a seam blow on an acrylic tank and pretty much 100% of the time, it's scrap. Acrylic isn't tolerant of repairs, the material crazes when it's stressed more than once and doesn't take repeated work well. An epoxy lined wood tank is seriously, incredibly durable. I did a test panel before I built my tank, where I poured the epoxy on a scrap panel of plywood to mimic the finished work product. I then took a 22 ounce demolition hammer and wailed on it as hard as I could over and over. There wasn't so much as a chip or crack. Try that with glass, or even acrylic. I could go on, but honestly I don't think it is even a valid argument, since I don't think there is ever a single "right" answer when this question is presented in a generic, theoretical manner. The only time this discussion makes sense is in the context of a specific person's preferences, tooling, experience, timeframe, and desire. I would never try to talk someone in (or out) of building a wood tank without knowing the whole context. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

12/18/2017, 05:28 PM	#7
ca1ore Grizzled & Cynical Join Date: Apr 2006 Location: Stamford, CT Posts: 17,319	A big plywood tank is far cheaper than a comparable glass or acrylic tank. Problem is they look like crap so have to be built in and longevity is debatable. I built one in 1992 and had oozing issues on and off. Broke it down in 1997. Was mynfirstbeffort, so perhaps builder error, but I bought a glass tank in 1988, and only retired it in 2008. __________________ Simon Got back into the hobby ..... planned to keep it simple ..... yeah, right ..... clearly I need a new plan! Pet peeve: anemones host clowns; clowns do not host anemones! Current Tank Info: 450 Reef; 120 refugium; 60 Frag Tank, 30 Introduction tank; multiple QTs

12/18/2017, 08:39 AM	#3
lyman28 Registered Member Join Date: Dec 2010 Posts: 60	Well that sucks. I had read all of the builds at one point and time and started rereading them and thinking I want to give it a go. Your tank was beautiful. What was the issue you had with your tank?

12/18/2017, 02:31 PM	#5
Scrubber_steve I'm really very likeable Join Date: Aug 2016 Location: Down Under Posts: 676	Personally, I don't get plywood tanks. Cost isn't a reason for building one over a glass tank. They are a lot of mucking around to build; need a lot of bracing - engineering consideration. One large plywood tank builder I spoke to agreed with me that he would have been better off building his tank out of concrete.

12/18/2017, 07:23 PM	#8
Scrubber_steve I'm really very likeable Join Date: Aug 2016 Location: Down Under Posts: 676	When I looked into building a plywood tank myself the costs were more than a glass tank. The cost of quality ply, plus epoxy coatings, etc. But the big expense was the cost of the single glass panel. You buy a glass tank from people that purchase full glass sheets at trade price. But if, for example, you go to the local glass merchant & get a quote for all the glass panels cut to size to make your own glass aquarium, its far more expensive than buying the aquarium ready made.. I found the cost of just the single panel of glass for the front of a plywood aquarium was as expensive as a retail glass aquarium of the same size. If i was going to make a very large aquarium (not something you would be moving around in the back of a pick up truck, but built on site) where full glass is out of the question I would use concrete panels. The wall thickness will be thinner than a plywood construction with all the necessary bracing, & bowing would simply be something you wouldn't need to be concerned about.

12/18/2017, 10:21 PM	#10
lyman28 Registered Member Join Date: Dec 2010 Posts: 60	I'm glad to know the issue with the tank was not catastrophic and easly repairable. Sounds like pouring the epoxy mitigates the risk more than brushing it on. I'll have to consider this. When I'm ready to start I won't be able to pour the sides if the tank is assembled. I would like to do a full 8 foot long tank and basement is only 7.5' high. Any idea how mattshacks's tank lasted with all of his seams? Part of me considered doing a 10' long tank but the seam makes me nervous. I'm looking at the plywood tank because it would be impossible to get at a tank the size I want into my basement. It won't happen.

12/19/2017, 10:57 AM	#11
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	I haven't had contact with Mattshack since he stopped updating his thread. Pouring adds an element of foolproofness. It's pretty much impossoble to do 3 or 4 pours, building to 1/8th of an inch or more, and still get a leak. The thickness also helps with durability from an impact perspective. If you can't accept a smaller tank I'd use glass mat on the walls and build up a good thickness the old fashioned way. I honestly don't like a lot of the wood tanks that aren't poured but I may be biased. Look at the boat building industry, it's common to build a really thick gelcoat finish on a wood or glass boat. Usually these are with polyester which isn't common on wood tanks but you can do the same with thickened epoxy. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman) Last edited by der_wille_zur_macht; 12/19/2017 at 07:25 PM. Reason: edited for typos

12/20/2017, 08:26 AM	#13
lyman28 Registered Member Join Date: Dec 2010 Posts: 60	Only other idea I had would be to pour the epoxy on the panels at same time before the tank was assembled. Do 3-4 pours that way, assemble so you still get the chemical bond. But it would be the epoxy acting like the glue. Screw it all together and then pour the fillets. I have enough clearance to to that on each seam.

12/20/2017, 08:49 AM	#14
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	I'm sure that would work if you had good joinery. I would probably let the panels cure completely and then use a router to machine the edges perfect, and another pass to remove the epoxy down to bare wood on the seams. Then use urethane (gorilla glue) and screws (predrilled) to assemble. Then pour fillets as you planned. I guess what I'm saying is that I trust urethane against bare wood more than I trust epoxy against cured epoxy. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

12/20/2017, 01:02 PM	#15
lyman28 Registered Member Join Date: Dec 2010 Posts: 60	How far in did the epoxy soak into the wood? If I routed the edges to bar wood, would there be enough epoxy soaked in to the panel intself to affect the strength of the gorilla glue?

12/20/2017, 02:00 PM	#16
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	Depends on the plywood. If you're using a hardwood veneer it'll probably just barely make it into the first core. No veneer, probably not energy though the first core. If I wasn't on my phone I would draw a diagram. I would route through the first 1/3rd or so of the plywood such that you're forming an open rabbet for the mating panel to sit against. This gives a bigger surface for the glue and also locks in the angle. The screws will hold it tight while the glue cures and the fillet will seal it. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

12/21/2017, 11:56 AM	#17
lyman28 Registered Member Join Date: Dec 2010 Posts: 60	Ok thanks. Off topic in a way but was wondering if you keeped an urchin with it? I thought I remember reading somewhere that an urchin can chew through the epoxy. Wondering if that is valid or not?

12/21/2017, 12:32 PM	#18
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	I did not. I've heard people theorize about that but don't know of a single confirmed example. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

12/21/2017, 02:47 PM	#19
oldhead Registered Member Join Date: Jan 2016 Location: New Jersey Posts: 527	I've seen a few of the newer plywood tanks using pond armor. It's already black and silicone will stick to it.

12/21/2017, 09:43 PM	#20
d-man Registered Member Join Date: Nov 2009 Location: San Diego, ca Posts: 2,732	I built my 860g, 220g sump, stand and canopy ribs for about $2400 total. In the process of taking it down to hopefully sell my house in next 6 months. I will 100% do a whole bother plywood build at my next place.

01/21/2018, 01:09 PM	#21
muttley000 MTS Sufferer! Join Date: Feb 2005 Location: NW Ohio Posts: 1,926	I did a 270 gallon sump using the pour method a few years ago and it has, and continues to perform fine. I am planning a basement build taller than the ceiling and hard come the the same conclusion Wille did. Pour the ends, router the rabbets, and assemble in place. Even though I won't be able to tilt it to a perfect 45 on the corner pours, I will still be able to get plenty of fillet contact by going a little deeper. __________________ Next step on the system is adding A 90 gallon! Current Tank Info: 475 multitank system is now running! Several hundred gallons of additions planned!