DIY polystyrene

@cknipe I think maybe going back to the cement idea might be the best. But what is the absolute correct way to mix cement for aquarium use? I have also seen those videos and would definately do a normal cement paste consistancy

 

Mix the cement as per the directions on the bag. The amount of water you mix into the cement, has a DRASTIC impact on the strength of the cement. My first try, I am going to mix 3 cement with 1 sand and only add enough water to make it a paste. The consistency / texture should be the same IMHO as the cement that you use for building or any other purposes....

 

BTW, I can't find anything on toxicity other than it's non-toxic to humans (but I'm still searching), but cretestone may also be a very good alternative to cement. It is a bit brittle (so you'll have to be careful working with it when dry), but it's much lighter and much easier (and messier) to work with than cement (alternatively sometimes called plaster cement, or primer cement. Almost always used to skim drywall / ceilings with).

I have some cretestone here left over from my days where I built my new add-on to the house, so maybe I'll mix some up, let it dry, and see what it does for a few weeks... Even have a spare tank to test it in.

EDIT: Main active increditiant is calcium sulphate dehydrate

From http://www.inchem.org/documents/sids/sids/10101414.pdf On page 25 the test results are shown specifically on aquatic fish (5 month period for testing) and no negative impacts was observed. It looks like it is safe to use. I've mixed a small cup (amount 500mg) and once dry I will clean it up and dump it in a tank with a fish or 5 to see what happens.

 

@cknipe the thing is the weight of the cement will help alot with the buoyancy of the polystyrene. Im really stuck with how I should go about waterproofing my design. Cement sounds like the best idea to me right now

 

Silicone?

 

Hey guys.

As you can see from my threads I ruled out every possible other option before I resorted to tearing the actual tank down.

When I decided to pull the gravel out as my last resort I immediately noticed that the base of the tank just did not look right. I could see even with water still in the tank that the Dura pond had actually started to break down. When I drained the tank to apply the new sealant, and climbed into the empty tank to paint the walls I got stuck to the base of the tank.

The paint had become sticky and wherever I touched it an imprint of my clothes was left in the coating.

My tank was built from plywood then coated with fiberglass. I used a special porous matting over the last stage of resin which is peeled off after curing, giving the finished product a very rough surface. Because of this I did not use any primers etc. I wanted as few chemicals in the water as possible. I used 4 coats of Dura Pond with 3 - 4 days drying time and waited at least ten days after the last coat before test filling. It stood with the test fill water at my shop for a week before I moved it home.

The Dura Pond was 100% adhered to the fiberglass resin. I was very impressed with the product when I used it and was very happy to use it again should the need arise. When I stripped the tank it was still totally adhered to the inside of the tank and would be impossible to remove.

I can not be 100% sure if something in my tap water caused an unexpected reaction with the DuraPond, I cannot be 100% sure if if I got a bad batch but, I can however say with absolute certainty that whatever killed my fish did in fact come from that particular tin of Dura Pond sealant. There was nothing else in contact with my water.

The tank is now built out of glass and I do my water changes in exactly the same way with the same treatments and my water is crystal clear. My fish are thriving and showing the best colours that I have ever seen on Malawis. I have not lost a single fish and I still use the same heater, lights, filter, rocks & gravel. The only thing that has changed is the tank.

I may very well have gotten an old/dud batch but I would never use the product again. I went through months of absolute hell because of it. I have been keeping fish for 15 years and had I not had previous positive experiences driving me to push on, I would have packed it in long ago. Watching a 20cm Milomo and a 20cm Borleyi that you raised from 4cm smash themselves to death on the lid of your tank is not something I ever wish to repeat.

By all means let your tank run with the stuff, it may very well be fine in your tank but just keep a close eye on things. If your water ever goes cloudy for no reason get your fish out of there! Unfortunately for me I had to find this all out by myself and learned the hard way, at least you guys know straight away what is happening. If you start to go down this road and can act quickly before it becomes a major issue.

I have posted this pic on other places on this forum but for me this little guy marks a huge victory for me and proves to me that I do actually know what I am doing in this hobby. My fish never looked like this in the previous tank.

 

Thank lcg for showing us your post. Zuraki is phoning them today and we will see where that goes. Ive been reading about cement and it seems it needs to be cured for a very long time. But maybe I could chuck it in the pool? I have the poly and wood stuck together just waiting for some way of water proofing

 

I just read an article on somebody using polyurethane varnish. What do you guys think??

 

Wana know what I think? I think you guys are over complicating this idea!

@nodac - Coming from someone who's built a DIY background already, i can assure you (aswell as all the other guys here thats built them before) that there is a much simpler way to finishing your background. If you interested, il take the time to build my idea of how your DIY should progress.

 

@L~C~G I can't see this from the post dates on your threads, but how long did you wait from when you panted the tank, untill you filled it up with water?

@ryanj252 definately agree. Especially pond paint, those things are MADE to be in water 24x7x365 - it shouldn't disolve. My mind is telling me that it has been applied incorrectly. Same for the cement "crumbling" story.

 

Yes, I must have put it on upside down

I waited a full ten days for it to cure before filling the first time and 48 Hours between coats.

Its your tank guys. Use it, dont use it..........its up to you, if you know more than me by all means go right ahead.

 

@ryanj252 please. I am very interested! I hae started this project and intend to finish it but I am really stuck at the waterproofing stage...

 

Not attacking or insulting you or anything - just want to get to the bottom of it. 10 days should definately be long enough... Multiple coats of paint? Waterprooving membrane?

I'm just stumped. I waterprooved an indoors garden bed that I *filled with water* to test for waterprooving, and I used simple waterprooving membrane with ruberized butimen because pond paint was too expensive. Can't use the ruberized butimen in fish tanks though as it's toxic (as far as I know), but pond paint is much better than butimen in any case.

 

Off topic, but here's a small sample of cretestone that I cast last night. It hasn't even cured for 24 hours yet, so I'm going to wait a day or two before dumping it into a test tank.



The finish is much smoother than cement, but it's easy to work with and carve. It's almost like dry potting clay that hasn't been fired yet.

 

I applied four coats with 48 hours drying time between. The insde of the tank was first coated with two layers of fiber glass matting. After adding the second coat of fiber glass I pressed a porous matting sheet into the resin which is pulled off after the resin has cured and leaves a very rough finish which allows the next coating of sealant to key to the surface.

All I know is that my water went murky, my fish died the most violent deaths you can imagine and the only thing left in the tank was water and a brand new heater. I now have a new glass tank containing water from the same tap running exactly the same equipment and my fish are in crystal clear water and are growing like crazy.

What dont you just seal that background with fiberglass resin? It cures totally inert and has been used for decades.

 

@L~C~G how much does fibreglass resin cost? And where is best to get it? I need to cover x2 poly pillars that are 56cm high 45cm wide nd 4.2cm thick

 

These guys are probably your best bet.
AMT Composites

Not 100% on the pricing, I know the matting was the really pricey part but you will have to give them a call and see.

 

I'm wondering. In your build thread, you mentioned the use of No More Nails? I'm wondering whether that didn't have anything to do with it. Their safety documentation states that whilst it can be indigested, it can cause a complete shutdown of the central nervious system - this will definately explain the violent fish deaths and erratic behaviour that you saw. Ofcourse no information available directly related to fish, but if prolonged exposure to humans can cause this, then fish getting it in 24x7x365 will most certainly be affected after a prolonged period of time.

My money would be on the glue, or alternatively when the pond paint cracked up, something toxic came out of the wood into the water - but I don't think you used treated wood if I recall correctly.

Anyways - going to move on now :bigsmile:

 

@cknipe so do you rate I go ahead with the durapond then or resin? Durapond is probably the cheapest option and the one I can get easily from a hardware store

 

The no more nails was isolated from the water by 4 layers of paint so it was never in contact with the water, but anything is possible.