Siliconing overflow to established tank?
 

What I plan to do is lower the water level 2 inches below where the bottom of the overflow will sit and silicone in the three-sided overflow but I have some concerns

When I silicone the Overflow how long should I wait before filling the tank back up?

Should I take all the tank inhabitants out of the tank including my two corals before doing this project?

What type of silicone should I use? Preferably something that's non- yellowing

I understand that silicone inside the tank will give off a strong odor but will this affect tank?

Thanks in advance to anyone that helps

This is doable (I've done it, actually) but risky. Uncured silicone is not safe for an aquarium and can poison the system. You need to be absolutely sure you don't drip any into the water while you're working, and you need to be sure it is fully cured before you refill the system.

Silicone cure times depends on the product. Read the label, and make sure you understand the bead size specified compared to what you're using. If it's claiming 48 hours for a 1/8" bead and you're using a 1/4" thick application, you may need 4 or 5 days.

The GE I and II products sold in home improvement stores will work fine, they're just not the absolute strongest - but for typical internal overflow box designs it's more than strong enough. Momentive RTV 108 is a silicone available through industrial supply (and amazon) that's stronger, if you want to be totally safe.

Thank you for your input, What would your opinion be about leaving the inhabitants in the tank? Should I move them to a separate tank ?

Way late on overflow plans there buddy..

Use vinegar cure (acetoxy) silicone.. cure 2-3 days more than likely at least...

If moving is an option its a no brainer..

I would move the animals if that is a option. Without knowing the size of the bead u will use it is hard to say how long it will take to fully cure, but I would go a minimum of 5 days but preferably 7 to 10 days. The type of silicone,bead size, temp & humidity all affect the cure time. So determining a exact cure time is difficult. Silicone is very toxic if it isn't fully cured so to me it is better to be safe then sorry.

Remember what der willie mentioned about the cure time on the label. Most of the labels on silicone state the cure time for a 1/8" bead. So if it says it cures in 48 hrs & u see a 1/4" bead then that would be a minimum of 4 days. I would always at the very least add a day or two to how long u figure it will take.

The acetoxy cure silicone that mcgyver mentioned cures a little faster & may not be quite as toxin as neutral cure silicone, but they are both toxic if they aren't fully cured. GE 1 is a acetoxy silicone so being u are on a time limit it may be a good option.

It is going to take a nice sized bead to silicone a acrylic box to a glass tank. Silicone doesn't adhere to acrylic good at all, so u will essentially be wedging the box in place with silicone. That will take a decent sized bead, so I would plan on atleast 5 to 10 days depending how big of a bead it ends up being

Thanks for all your help. I think im going to try the rtv108 willie recommended. I heard its grade A stuff and is military tested tough 😁. Im going to move my animals to a 10 gallon for the mean time and use a garbage bag taped to the glass to avoid silicone fumes and material entering the tank. When i lower my water level i might remove my rockwork, do you think it will effect the beneficial bacteria if it doesnt have an ammonia source and
I remove my rocks . My tank has only been up for 8 weeks and Also my sump will be disconnected from my tank too. In advance i appreciate all the help

Nah i just have to do extra work cause i didnt think about it sooner. Thanks for the advice 💪

I agree with the others, if you can move the animals and totally drain the system, you should absolutely do that.

RTV 108 is acetyl cure so it's fairly fast (in the world of silicone cure times).

Any time I do silicone work, I lay a couple beads on a piece of paper towel or a paper plate or something else disposable. I make them the same size as the beads on the work piece. Then, if I want to know if the silicone is cured, I can cut one of the test beads and see if it's totally cured throughout or still soft in the middle. Saves a lot of worry over guessing cure times, especially if you're in a rush.

For better grip to the acrylic you can roughen up the surface area on the box where the silicone will contact with sandpaper, dremel, etc...

Here's a pic from when I did mine recently. http://www.reefcentral.com/forums/sh...php?p=25164984


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Drain the tank? Is that absolutely necessary?can i get away with putting all the water in a garbage can until the silicone cures? Also ive been looking at tbe msds report on 108 and it says its not to be emerged under water :confused:

Do you guys think running a humidifier will speed up the silicone curing process? Just a thought

Silly question but the overflow box doesn't need a watertight attachment to the glass. Couple drops crazy glue in a few spots to hold it in place?? Or silicone a back onto the overflow. Make it four sided.


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Why don't you just buy a shadow overflow? They don't need to be glued. They use bulkheads. That way all you need to do is drill.

Roy

I cant cause i made the mistake of gluing the elbow outside of my tank so im unable to take out the bulkhead without cutting the pvc.which is why i decided to go with the 3 sided option

All silicone says it isn't intended to be submergered underwater. That is why on a tank the most important part is the seams inbetween the panes of glass. The seals on the inside corners of the tank are there to protect the seams & keep them from water.

The rtv silicone is one of the strongest U can get. It is a adhesives & not just a sealant like some silicones. It will bond to the glass great but I don't think it will adhere to the acrylic any better then other silicones. When u silicone the box just imagine wedging the box in place with the silicone. I don't know if u have looked but the only place local to me that carries the rtv is grainger. U will probably have to order it online. Honestly, for what u are doing I think any of the dap aquarium safe silicone that u can get from the big box stores will be fine. I would get the dap aquarium safe silicone because u know it isn't a neutral cure silicone

Your beneficial bacteria will be fine for the week that u don't have fish in the tank, so that is not a worry unless u don't let the silicone cure before refilling the tank.

What size tank do u have? That looks like a really small overflow. I do think that on a tank that is already setupthe best option is a overflow that is held on by the bulkheads

I would argue the opposite, why spend the money when you can silicone one on for next to nothing... granted hes depicting a premade overflox box which costs, so it maybe a moot at that point. Isuppose my point is theres obviously different strokes for different folks but theres nothing inheritly wrong with attaching the box to his tank. I'd say go for it :)

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Some designs do, for examplemine did with no bulkheads used on the overflow box connection to my DT.

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I want to avoid water leaking into the overflow in the event of a power outtage it will only allow the water the the overflow to be siphoned

I decided to go with the 4 sided bulk head mounting overflow. I have the cut the pvc before my T fitting but it will save me curing time and moving the fish. Thanks everyone for all of your help.

I really do think that is your best option. It would be a lot easier & safer to just redo some plumbing. If u have to drill the holes then u would still need to drain the tank, but once u are done u can fill it back up & get the fish back into the tank instead of having to wait 5 to 10 days

Yea. My tank is already drilled. It just has that white pvc elbow inside making it look like a tank at a pet store and i want to change that because its an eye sore. The whole acrylic to glass, silicone not sticking ordeal is making me super iffy but plus having to deal with curing :fun5: at least i know what to expect next tank setup

Not sure if it was mentioned, but with an enclosed box you attach with a bulkhead you really should have two gaskets to do it properly. The stack should be: bulkhead flange | gasket | overflow hole | gasket | tank hole | bulkhead nut.

No it wasnt mentioned. Thanks for the tip im ordering an extra gasket now. It makes sense to do it that way