schoondy Posted April 21, 2006 Share Posted April 21, 2006 Hi there everyone I'm about to make my own diy concrete background. And have read a few diy articles where they sometimes sudgest using expanda foam So the other day I went to bunnings and got this Bostik expanda foam, but after reading it on the back it says expanda foam should not be immersed in water ???? Does anybody know if this expanda foam will be ok or will it turn my water toxic and if this is not the right expanda foam what brand should I get Any information on this would be much appreciated Cheers Martin Link to comment Share on other sites More sharing options...
LucifersJester Posted April 21, 2006 Share Posted April 21, 2006 I've never used expanda foam on my tank backgrounds... I used styro foam, and then cemented it and then used two part marine grade expoxy sealant (the foam safe one) and I have never had any problems... I would say if you used the expanding foam, and then painted or did what ever you had to and then used the same two part exposy sealant and made sure there was a good coat all over it then there shouldn't be a problem... But I would always do a test first - unless someone else has already done it and you trust what they say... Just my 2 Cents... Link to comment Share on other sites More sharing options...
schoondy Posted April 21, 2006 Author Share Posted April 21, 2006 Hi there thanks for the reply sounds like a good idea to cover it with marine epoxy. How much do you think I will need for background measuring 1100 x 410 Would 1 liter be enough and did you just paint this straight on or did you also use fiberglass mating to make it stronger ? Any more info on this would be much appreciated ..........cheers Martin Link to comment Share on other sites More sharing options...
anchar Posted April 22, 2006 Share Posted April 22, 2006 I used Waterlife (I think) expanding foam which is especially made for aquarium use (very expensive). I have read that the Sellleys product is equitable and much cheaper. You need to remember that they have cyanide in them so it must be cured properly. Also another useful point....once you fill your aquarium with water, be prepared for it to lift away from the glass and float up. If you are covering it with concrete it may stay put. Otherwise, if it lifts, you will need to drain the tank, dry and apply a large amount of aquarium safe silicon to affix it. I will try to find some pictures of one I made a few years ago. Andrea Link to comment Share on other sites More sharing options...
schoondy Posted April 23, 2006 Author Share Posted April 23, 2006 Thanks for the advice Andrea I will definitely glue the background as I don't want it to float away. I have decided to go with just foam and concrete for now and aquarium save silicone and still debating about puting on a coat of apoxi as I learn later its not really needed. It just means i've got to do daily water changes for a week or so till ph drops to 8.5 Thanks again for all the advice and would love to see a pic of your tank if not to much trouble Kind regards Martin Link to comment Share on other sites More sharing options...
anchar Posted April 23, 2006 Share Posted April 23, 2006 It took nearly 2 months for my pH to stabilise in a concrete coated poly tank. It is now steady at 7.8 (without substrate or any buffers). I used a lot of concrete though. Still trying to find the pics. for you. Andrea Link to comment Share on other sites More sharing options...
schoondy Posted April 24, 2006 Author Share Posted April 24, 2006 Wow didn't expect it to take 2 months to cure but ill bet the results where well worth it. I just started on my background cut out the foam decided not to use expander foam and am now up to gluing the small pieces of foam to background. Just hope it all turns out ok lol Cheers Martin Link to comment Share on other sites More sharing options...
anchar Posted April 24, 2006 Share Posted April 24, 2006 To be honest I threw it in the backyard and dumped the water maybe 10 times in the fews few weeks then left it. It is possible that it took a shorter time to cure but i was too lazy to change water each day. Andrea Link to comment Share on other sites More sharing options...
Simonauv Posted April 27, 2006 Share Posted April 27, 2006 Some time ago I found instructions to make a background from expanding foam. They mixed the foam (no brand mentioned - it was a UK publication) and when set and shaped they began coating it with several coats of marine epoxy and on the final coat they threw sand on it to texture it. You need to coat the back though as well as it will leach chemicals into your water from the back too. On a little bit of a different note; has anyone ever tried using hebel blocks in their tanks? It would float and would need to be glued down but can be carved real easy too. Link to comment Share on other sites More sharing options...
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