# Drylok concrete waterproofer fish safe?



## maximusfish

Looking for a sealer for my fibreglass 3d background. It is raising my tank water ph. Has anyone used the clear drylok sealer? Internet search shows some people have used this one, latex based.

If not, other suggestions for a sealer? I like my background and don't want to ditch it, but it is for a shrimp tank and the ph keeps climbing to 7.8


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## Daryl

I'm not on my PC at the moment, but when I get there I can post a link to a thread about using drylock to seal a plywood tank. I believe it is fish safe, but ultimately did not work at sealing the tank...

Other ideas could be a marine or potable epoxy? I looked into the epoxy years ago but ditched the idea due to the cost - it wasn't so much that it was pricey, but rather the smallest size I could find for purchase was quite large & expensive and more than 95% would have gone to waste.


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## maximusfish

Thanks!
My sister has some West System 105 epoxy left over from her kayak build, but I was unable to find confirmation that it was ok.


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## Daryl

Okay, sorry for so long between posts - finally found a moment to sit with the laptop so I could paste this link from my favourites;

1122.08 GALLON TANK PROJECT!!! â€¢ Cichlid-Forum

It's an epic thread - I was fortunate enough to be involved with it when it was happening and recently re-read it from start to finish.

Long story short: he used drylock over hardy-panel, but eventually the tank leaked due to a couple of design mistakes. In the end he re-coated the entire thing with pond armor. As far as I know it's still running 9 years later.

West Systems 2 part epoxy may be okay. Keep in mind that if these companies have not specifically tested something for aquarium use they will most likely never say it's aquarium safe for liability reasons.... I think the better question to ask is if their product is "potable". I seem to recall that west system does have a potable epoxy product - but like I said, it came in large pails and was quite pricey.


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## Hammer

Funny, I was looking into something similar. Did a DIY rock background for an African tank. I liked it and five years later, I still like it and want to keep it for a planted tank. The background has been in an established tank for 5 years. It is a styro and sika (latex mix concrete) build. Took out all my argonite and replaced with pool sand w/ some play sand. Tested my Ph and it's 8 (my tap water is 7). I'm attributing it to the background, but it should have long stabilized. In the beginning, I even added vinegar and have done hundreds of water changes. So, looking for similar answers. I would be hesitant to use an epoxy or resin based sealant because of prolonged exposure maybe put chemicals into the water. I know in a normal application, a kayak or boat hull, sealant for massive amount of water, it's pretty stable, but when soaking in the same warm 50 gallons of water, I don't know.


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## maximusfish

I had this background in two tanks, both were display tanks at an lfs so had been submerged for several years. I wanted to use one for a shrimp tank, and when I tested the ph of the set up it was 7.8. I broke down the tank and tested each component separately. The rocks and sand were inert, but the background raised the ph from 6.4 to 7.8 overnight. It had a distinct petrochemical smell. It is a fibreglass background, painted and the paint peeling. Not diy.

The second background was in a tank I was using for apistos. I had been fighting a high ph, so I removed this from the tank. I soaked the background in a low tray with just enough water to cover it and left it for a few days. The ph only rose to 7.4 from tap 6.4, KH and GH were only 2-3. This one did not have the chemical smell, but the paint was flaking off.

Definitely not comfortable using these backgrounds unless I can seal them. It may be the paint that has broken down after being in water for years, rather than the background itself, that is causing the problem.

Someone suggested coating with a layer of aquarium safe clear silicone, which might work if there is a way to thin it so it can be painted on in thin coats.


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## Hammer

With low water hardness, I am wondering what is bringing up your ph?? Your fish choice is really close to what I want, (dwarf cichlids, tetras etc). But, I'm worrying about my ph too. I like my background, looks great, but my ph is now 7.6 still too high I think. after all this time, it should be inert. Maybe yours is actually starting to chemically degrade...I do not know. I will follow and maybe someone will come up with a coating or additive to make it inert.


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## coppercloud

What about using Co2? The plants would love it.


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## Hammer

I am definitely going Co2. I wonder if C02 drops hardness by reacting with calcium. The more I think about Maximusfish's description of petrocehmical smell and changing ph, I think there's something else going on with the chemcial structure of the background. Maybe time to turf it a chemical smell is never good.

I can only speak about the Sika latex/concrete product, which does seem to stabilize after some time (at arounbd 7.6/ 7.8...hence my part in this thread). I have seen concrete "stump" backgrounds which used sealers online. If I remember, the project was used in a SA tank, which suggests the water parameters was considered.

Best luck Maximusfish, I keep following in case something comes up.

Hammer 

That might be a place to look.


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## maximusfish

I was reading about flowable silicone, and will contact the company to see if it is fish safe. I have apisto cacatuoides, and they have spawned and raised fry at the higher ph. I read that they are one of the few SA dwarf cichlids that can tolerate more alkaline water, ph from 6.5 to 8.


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## maximusfish

Just heard about Liquid Plastic, polyurethane coating, comes in a spray can. I was told by someone who has used this on a 3d background that it is fish safe.


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