# Drylok DIY background questions



## 702Cichlid (Feb 28, 2010)

Hi all was getting ready to design my first diy background using white styrofoam and colored drylok and I just had a few questions about some fundamental design concerns.

1. When designing for height is it more desirable to have the background abutting the tank bottom or to leave room for substrate underneath it?

2. My background will be used to obscure my canister intakes and heaters so I wonder when hollowing out the recesses what is the minimum thickness of styrofoam I need to maintain structural integrity and since a portion of that stryofoam cannot be siliconed against the glass what can be done to make sure those pieces remain attached against the force ofbtheir own buoyancy?

3. I will be using two rena smartheaters which are double plastic encased...since they don't expose a heating element do I need to be concerned about clearance of styrofoam walls from the heater?

4. When providing holes for water flow to the intake (and trying to keep them fry safe but waste removal efficient) what is the best method that stresses flow and waste removal primarily with fry safety a secondary precaution. I will be running 2 xp3 filstars on a 90 gallon tank so any empirical advice would be great.

5. Should all exposed foam be dryloked? Or is it better to leave the backs uncoated for silicone adherence?

6. I will be cutting my background into pieces and was wondering when I reassemble them in the tank should I silicone the pieces to each other as well as the tank back?

7. Last question is the drylok all I need to finish the background (no other waterproofing or epoxy needed) and can I use the drylok on other aquarium decorations such as cichlid stones or rocks without any danger?

Once again thanks for all the help... The community here rules!


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## mightyevil (Oct 23, 2008)

Okay, here we go...

1. It is really a matter of preference but keep in mind that the fish will dig sand up and possibly expose the bottom edge of the background making it an eye sore. I would recommend to build the background as low and as high as you can.

2. I have gone as thin as .5" with no problem but I do not lean any rocks or decoration against it. Use your judgement and keep in mind water preassure. When carving out the sections where the intakes will go, make sure that you carve it in the middle or close to the middle of that background section. In fact, I would cut the background into esctions first and then carve the sections for your intakes, this will make choosing the right place for carving easier.

3. I use exposed heaters (persay) and I have never had an issue with them melting styrofoam, I imagine that those smart heaters will be even safer due to the encasings.

4. I have found the following to be the most convenient to use for the DIY background application. The remain nice and clean and the waterflow to my HOB filters is great. 








You can make these with pieces of PVC some plastic window screen/mesh and silicone. Wrap the window mesh around the PVC like in the picture, secure it with a rubber band, apply silicone, let silicone cure, take rubber band off, make holes of the same size in background, apply silicone on walls of holes and finally slide the "gutters" in place... oh and let silicone cure again, of coarse.

5. I like to leave the back of my background uncoated, I do think that adhearence is better this way although Drylok does bond well with the styro. My recommendation is Drylok all styro except the back where silicone will go.

6. Yes, I would recommend siliconing the pieces together. The chance of one piece becoming dislodged from the glass is greater when the pieces are not siliconed together IMO. This will also prevent small fish from getting stuck between the pieces and potentially getting all the way to the back of the background and getting stuck there.

7. The Drylok is all you need, once dry it is good for use. I assume that using Drylok on other decoration is safe, only way it would not be safe is if it causes a chemical reaction with the object that it is applied on but I highly doubt it would happen with aquarium decorations. Additionally, Drylok is a waterproofer so my assumption is that if applied to a rock or any other object it would actually seal it and since Drylok is safe in water after curing, then any object covered in Drylok would be safe for aquarium use. That would be my theory...


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## dacjr (Feb 12, 2010)

I just finished a BG for a 10 gallon (wanted to try it on a small tank before my 110), and I used drylok...very easy. I mixed in some quikrete color. One coat for the base, one a little lighter for highlighting, and finally just drylok for a the final touch. Painted all but the back. The thinnest portion of mine ended up at about 1/2" where the intake is hidden, and it worked out okay. Mine ended up being almost 1/2" off of the tank bottom, which I'm sure I will regret, but that's why I tested it out first. Anyway, I found the whole process really cool, the background turned out amazing! Now I'm working on my 110, and I'm not sure if I enjoy keeping fish or creating BGs more :lol:


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## 702Cichlid (Feb 28, 2010)

Mighty you are awesome, thank you so much for taking time to answer all my questions!


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## hydro4892 (Jul 4, 2010)

This was extremely helpful, I am going to try and make my first background for my 125 gallon. The only thing I still need help with is the materials.... oh and when you carve out the whole background, you just add the drylock on and thats it? Any certain amount of coats? Also, what type of syrofoam is safe for fish? The materials I have are: styrofoam, GE silicone 1, tools to carve the styrofoam, and drylock(is any kind ok?) Am I missing anything? Thanks!


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## Slee (Oct 19, 2010)

I recomend using either the "blue" Dow or the "pink" Owens corning for foam due to the fact it is a closed cell styrofoam and the white "beadboard" styrofoam is an open cell styrofoam. The closed cell styrofoam is a more stable product when placing underwater for a long period of time. I just finished the carving for my BG I found out that using a sawzall blade and a wire cup brush in a drill, then I hit the carved area with a lighter and melted the rough edges down a little bit it also seamed to make the foam a little more rigid after doing this. Check on the side of the can to make sure its a laytex based product and it should say safe for pools or ponds and you should be good to go. The can I have I bought like 5 years ago for painting my basement wall that I thought I had a water issue with however I didnt so now im finding a use for it.


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## hydro4892 (Jul 4, 2010)

Cool thanks a lot!


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## TropheusFriend (May 15, 2005)

So, has anyone had experience doing this with Tropheus? Since they are major herbivores, was wondering if they take chunks outta the styrofoam since the Dry-Lok doesn't get hard or anything!


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## theoryguru (Oct 11, 2011)

There was a thread about plecos damaging a DIY bg and I don't recall reading anyone reporting any major damage.
I had some pacus that nibbled an edge of my bg, but that's it. 
Just be mindful not to hit the bg while vacuuming or moving rocks around.


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