Tank to Sump Ratio

[Chris Atkinson]

Greetings Reef fans,

As I await the arrival of my skimmer, return pump, powerhead, plumbing, etc. I am wondering about how to size my sump.

I have a 75 gallon Glass Aquarium for display on a fully enclosed cabinet. I will conceal the sump below. I have access to a 20 gallon long aquarium for a sump, but am wondering if after putting in my skimmer and pump, if my refugium area will be too small (accounting for bubble trap baffles)

My apologies if this has been posted here before. (probably somewhere on the database)

Any suggestions or thoughts on the ideal sump capacity versus display?

I'm leaning towards trying to glue up my own acrylic from scratch, but am a bit intimidated by the prospect of this job.

Thanks, Chris

[Gary Majchrzak]

there's no recommended ratio per se.

Obviously, some sumps (and refugia) are more efficient/productive than others but size isn't everything.

The most important thing about a sump is the fact that it must be designed large enough to catch and hold ALL water that drains to it in the event of a power outage.
I hope this helps, Chris.

Welcome to RC!

[drparker]

To Reef Central
1 to 2, 150 gal sump would be a great size for 75g system. what I really mean is the larger the better. A 20 will do, a 36" long 29 will give you more space.

[reeftanknewbie]

+1 for both responses. When I lived in California, old reef keepers would use the 25% rule of thumb (that the sump should be at least 25% the size of the tank). So no smaller then what you have but like others have said the larger the better as the sump/refugium increases the total water volume in the tank plus a great place to hide things like your heater, skimmer, etc.

[Chris Atkinson]

Originally Posted by Gary Majchrzak

there's no recommended ratio per se.

Obviously, some sumps (and refugia) are more efficient/productive than others but size isn't everything.

The most important thing about a sump is the fact that it must be designed large enough to catch and hold ALL water that drains to it in the event of a power outage.
I hope this helps, Chris.

Welcome to RC!

Gary and the rest....THANKS! This makes perfect sense. This is a very critical part of why I want to make it "big enough"....what I don't quite understand is exactly how much additional volume do I need to account for power outage drainage? (Rhetorical, I don't expect you to know!)

I'll have an overflow box - (it is not pre-drilled and I'm not messing with drilling in the glass). I'll have a check valve on the outlet side of my return pump, so backflow into sump for power loss should be minimal. On the supply line from overflow box to the sump, I realize that the tank will drop until siphon is lost. So the volume of water returning to the sump with power loss is the total volume of the supply line, plus the tank level drop.

This is where I'm a bit confused. Tank level drop with power loss and just how much that will be. I realize the tank will "seek its own level" when the sump and pump system are running normally and flows equalize. (which is why with this system the tank level "never changes" and you handle evaopration and topoff with sump levels) What I don't quite understand is just how much the level will drop from normal operation until the siphon is lost due to pump failure, power outage, etc.

I've bought the CPR model overflow box rated for 800 GPH, I believe. I intend to drill some holes just below the water level for a siphon break, if there is not already something there. I'll wait until it arrives to study the design.

One idea I've considered is setting the tank up with tapwater and no rock. Putting my return pump and overflow box in, and using a bucket as the temporary sump to establish flowrates. Then, I can have a known volume in the bucket, kill the power, and measure the amount it rises....having spare empty drain collection capacity available (more buckets) in case something goes awry....

Seems like this will work.

Is there anyone with an overflow box that has tips on just how much the water level drops in the event of a power outage? (particularly anyone running the CPR 800 GPH box)

Thanks! Chris

[Gary Majchrzak]

water level will drop to the lowest point of overflow or until siphon break.

To figure water volume in gallons use length x height x width (in inches) and divide by 231.

In other words, say the water level in your (48" x 18" x 20") 75 gallon tank drops one inch when the power goes out.

48" x 18" x 1" / 231 = 3.74 gallons will drain to the sump.

Now add in the water that will be in the plumbing- perhaps another 2 gallons.
Got anything else that will be draing water? Add it!

[Chris Atkinson]

Originally Posted by Gary Majchrzak

water level will drop to the lowest point of overflow or until siphon break.

To figure water volume in gallons use length x height x width (in inches) and divide by 231.

In other words, say the water level in your (48" x 18" x 20") 75 gallon tank drops one inch when the power goes out.

48" x 18" x 1" / 231 = 3.74 gallons will drain to the sump.

Now add in the water that will be in the plumbing- perhaps another 2 gallons.
Got anything else that will be draing water? Add it!

Hey Gary,

I just realized you're in Ra-cha-cha! I got my first 55 Gal long salt tank when I lived in Charlotte on Boxart street up next to the Gennesee river. This was in the late 80's back when Arthur Shawcross was on his serial crime spree putting heavy bio-load in the river.

Back then it was undergravel filters, powerheads and an aquaclear powerfilter hung on the back.

Is "Brother Weez" still the morning D.J.? (My hunch is he's long-gone from the airwaves by now.)

I ran all around the local petshops back then, pre-internet, poking around and picking folks' brains. I bet we may have crossed paths back then!

Thanks for the feedback. And yes, you have really pinned down my true question: I'm wondering how much my display tank level will drop in the event of a power failure. I can calculate the associated gallons. I just don't know how much of a tank level drop to expect with power loss.

Thanks! Chris

[Chris Atkinson]

Originally Posted by Gary Majchrzak

water level will drop to the lowest point of overflow or until siphon break.

To figure water volume in gallons use length x height x width (in inches) and divide by 231.

In other words, say the water level in your (48" x 18" x 20") 75 gallon tank drops one inch when the power goes out.

48" x 18" x 1" / 231 = 3.74 gallons will drain to the sump.

Now add in the water that will be in the plumbing- perhaps another 2 gallons.
Got anything else that will be draing water? Add it!

Hey Gary,

I just realized you're in Ra-cha-cha! I got my first 55 Gal long salt tank when I lived in Charlotte on Boxart street up next to the Gennesee river. This was in the late 80's back when Arthur Shawcross was on his serial crime spree putting heavy bio-load in the river.

Back then it was undergravel filters, powerheads and an aquaclear powerfilter hung on the back. I don't recall ever hearing about a protein skimmer, sump or refugium back then.

I shut down my 55 undergravel unit in the mid 90's after relocating it to Lake George and wound up getting out of the aquarium hobby for several years. I'm just getting this new 75 fired back up.

Is "Brother Weez" still the morning D.J.? (My hunch is he's long-gone from the airwaves by now.)

I ran all around the local petshops back then, pre-internet, poking around and picking folks' brains. I bet we may have crossed paths back then!

Thanks for the feedback. And yes, you have really pinned down my true question: I'm wondering how much my display tank level will drop in the event of a power failure. I can calculate the associated gallons. I just don't know how much of a tank level drop to expect with power loss.

Thanks! Chris

[Gary Majchrzak]

I used to go to 'Whirlwind Music' on Boxart.
Visited Lake George 6 months ago.
Shawcross is dead and Weeze is on another station nowadays.

So much for catching you up!

If all else fails you can always simulate a power outage and see how much water drains to the sump

[dwd5813]

i think gary's suggested simulated power outage is probably the best way to figure it unless you can identify the exact level that the tank will run at and the exact level it will be when the siphon breaks and calculate the volume held in plumbing. you'd pretty much have to do the power out test to figure most of that anyway, i think, so there you have it. just keep in mind that the sump has to hold it's running volume plus the overflow from the tank and displacement from any equipment parts that aren't run submerged like the upper part of the skimmer body, and plan accordingly.

as far as what size is best, i'd say that the only restrictions i can really think of is the above for containment and the available space. i certainly don't have an exact ratio, but if you think of natural reefs vs. the volume of ocean and amount of inshore type habitats that refugiums can simulate, it's pretty astounding. i for one would love to set up a system where the typical ratio of display to sump/fuge is reversed and the fuge is gigantic by comparison.

[drparker]

When you do simulate the power outage try this; after the tank drains into the sump with every off, Add enough saltwater to the sump to fill it almost to the top. Now turn everything back on and let it run for a few minutes and stabilize the water level in the sump. Mark this water line in the sump with a sharpie on the side where it's easy to see. Next pull water out to return to your normal sump running level. The line is your "fail-safe", with a quick look you'll know your safe from a flood as long as your running sump level is below it.

[Chris Atkinson]

Originally Posted by drparker

When you do simulate the power outage try this; after the tank drains into the sump with every off, Add enough saltwater to the sump to fill it almost to the top. Now turn everything back on and let it run for a few minutes and stabilize the water level in the sump. Mark this water line in the sump with a sharpie on the side where it's easy to see. Next pull water out to return to your normal sump running level. The line is your "fail-safe", with a quick look you'll know your safe from a flood as long as your running sump level is below it.

DRP,

That is brilliant! I love it! I need to bookmark this thread as this forum is so popular stuff runs off the page fast!

So, I'm trying to think this through.....if I do this "fail safe" mark....and then a while after I get it figured up and make my sharpie mark, I add a bunch of liverock or other liquid-displacing items to the sump, that changes the whole thing, right? (or is that not right? ) I'm trying to wrap my mind around it and am almost thinking I'd have to run the experiement both ways to verify what's real!

[Gary Majchrzak]

Originally Posted by Chris Atkinson

So, I'm trying to think this through.....if I do this "fail safe" mark....and then a while after I get it figured up and make my sharpie mark, I add a bunch of liverock or other liquid-displacing items to the sump, that changes the whole thing, right?

correct.

[khaosinc]

Originally Posted by Chris Atkinson

DRP,

That is brilliant! I love it! I need to bookmark this thread as this forum is so popular stuff runs off the page fast!

So, I'm trying to think this through.....if I do this "fail safe" mark....and then a while after I get it figured up and make my sharpie mark, I add a bunch of liverock or other liquid-displacing items to the sump, that changes the whole thing, right? (or is that not right? ) I'm trying to wrap my mind around it and am almost thinking I'd have to run the experiement both ways to verify what's real!

other than needing to keep them in the water, the level is the issue and not whats in the sump if I understand everything. Also if you are going a large enough for seperate chambers, keep in mind only where the return pump is will be lower.

easiest thing to do is simply get it all running, and unplug it the return. should tell you everything.

[drparker]

Originally Posted by Chris Atkinson

DRP,

That is brilliant! I love it! I need to bookmark this thread as this forum is so popular stuff runs off the page fast!

So, I'm trying to think this through.....if I do this "fail safe" mark....and then a while after I get it figured up and make my sharpie mark, I add a bunch of liverock or other liquid-displacing items to the sump, that changes the whole thing, right? (or is that not right? ) I'm trying to wrap my mind around it and am almost thinking I'd have to run the experiement both ways to verify what's real!

Not really, your going from all the way full down to the water level once the pipes are full and the overflows and skimmer running. So the line really doesn't change. A typical sump is run at a level below this line. mine is 3" lower. So when I add or remove stuff that regular line changes but not my fail safe.

Where it can help is if you place a bunch of rock in your sump and now your normal line rises above the fail safe you know you'll have a flood if you lose power.

[Gracekain]

Originally Posted by drparker

When you do simulate the power outage try this; after the tank drains into the sump with every off, Add enough saltwater to the sump to fill it almost to the top. Now turn everything back on and let it run for a few minutes and stabilize the water level in the sump. Mark this water line in the sump with a sharpie on the side where it's easy to see. Next, pull water out to return to your normal sump running level. The line is your "fail-safe", with a quick look you'll know your safe from a flood as long as your running sump level is below it.

I hate to resurrect old threads but... This may be common knowledge to most here but I am researching the best way to set up my first sump and this is the information I was looking for and it is a great idea on how to determine how much water can be held in your sump in the event of an outage.