Olly Posted October 11, 2008 Report Share Posted October 11, 2008 After researching ways to get/make a decent size tank, it looks like plywood is going to be the easiest and cheapest way for me to get a bigger tank. I have come up with this design, with a filter built into the side of the tank. I would use 3/4" marine grade ply for the inner surface and 10mm glass. In between the two sheets of ply I will put insulation (pink batts or similar) and use 3/8"-1/2" ply on the outside. Measurements are just estimates at this point, but its going to be 600L+ Would this work? Have I missed anything out? It will need waterproofing on the inside, what would be the best product(s) to use? Quote Link to comment Share on other sites More sharing options...
markvs Posted October 11, 2008 Report Share Posted October 11, 2008 i would suggest that the size of the glass be increased. My4ft'rs are 10mm , so if you want bigger, then, surely thicker glass would be needed? I recently saw an 8ft'r it was about 15 mm thick. Quote Link to comment Share on other sites More sharing options...
suphew Posted October 11, 2008 Report Share Posted October 11, 2008 The thickness of the glass is calculated on the height of the tank not the length, this is because bowing in the length is taken care of using braces, but you can't brace height. I'm not convinced that for a tank this small you will save any money, unless you have access to free plywood, fiberglass, etc. If you go direct to a tank maker it should only cost you $600. I haven't priced up these things in a while but a quick guess, pinkbats $100 a bag, plywood $100+ each sheet and you will need 2-3, then add your glass, sealer (fiberglass), glue, stainless steel screws, timber for bracing, etc etc Quote Link to comment Share on other sites More sharing options...
Stella Posted October 11, 2008 Report Share Posted October 11, 2008 From my understanding 'marine grade ply' does not mean it is water-proof/resistant etc, but rather it is designed to be bendable, like for on the sides of boats. Marine grade is often mentioned in regards to tanks/stands but is not necessarily what you want. Quote Link to comment Share on other sites More sharing options...
David R Posted October 11, 2008 Report Share Posted October 11, 2008 Stella is right about the marine ply, its designed to be heated and curved to make boats. You want H3 treated ply. You'll need to build a wooden frame to support the ply, and line it with pond liner or fibreglass. Have a read through the DIY forum on www.monsterfishkeepers.com as there are many people who have built wooden tanks on there. Quote Link to comment Share on other sites More sharing options...
Olly Posted October 11, 2008 Author Report Share Posted October 11, 2008 I can get free ply, wood for frames and pinkbats. I will just need to buy the glass and pond liner or fibreglass H3 is quite toxic isnt it? I'd be scared that it would get into the water somehow. Marine grade is good quality stuff that has few defects, unlike some other grades I've used in the past MFK is good I have been looking there already Quote Link to comment Share on other sites More sharing options...
David R Posted October 11, 2008 Report Share Posted October 11, 2008 If the H3 treatment is getting into the water then I'd be more concerned about the water getting into the plywood and causing it to rot... Quote Link to comment Share on other sites More sharing options...
Olly Posted October 11, 2008 Author Report Share Posted October 11, 2008 If the H3 treatment is getting into the water then I'd be more concerned about the water getting into the plywood and causing it to rot... thats true. would fibreglass, the same as on a surfboard be good enough? Quote Link to comment Share on other sites More sharing options...
ryanjury Posted October 12, 2008 Report Share Posted October 12, 2008 Isn't the fibreglass resin and stuff really expensive especially considering the area's you would have to cover? Even second hand you should be able to pick up a 5x2x2 (540L) for $100-200? Have seen 6fter's go for around this? Have you asked around the petshop's for prices? Or contacted Peter at port nickolson glass in Welly.. Obviously if you just want a project then it would be wicked Quote Link to comment Share on other sites More sharing options...
Ira Posted October 12, 2008 Report Share Posted October 12, 2008 I wouldn't bother with going something unusual like ply unless you're doing it just because you want to. It could look nice if you do the woodwork well. But there's no point otherwise as that really not a particularly large tank. Quote Link to comment Share on other sites More sharing options...
David R Posted October 12, 2008 Report Share Posted October 12, 2008 I agree with Ryan that its probably more hassle than its worth unless you're going really big. My 150x70x60 tank in 12mm with a hole and overflow was only $380. When we eventually settle down I'm planning an indoor pond [with a viewing window or two] around 8x4x2.5', at that size glass would be bloody expensive and heavy, so timber is a better option. Greg only charges around $350-400 for a standard 6x2x2' tank, so its probably not worth building your own at that size. Quote Link to comment Share on other sites More sharing options...
richms Posted October 16, 2008 Report Share Posted October 16, 2008 Your time has to factor into it as well, and at the end of it you have some ugly tank with minimal resale value IMO. Quote Link to comment Share on other sites More sharing options...
Ira Posted October 16, 2008 Report Share Posted October 16, 2008 Your time has to factor into it as well, and at the end of it you have some ugly tank with minimal resale value IMO. Really depends on how good of a job you do on the wood. Of course, using something other than plywood would help heaps. Quote Link to comment Share on other sites More sharing options...
smidey Posted October 16, 2008 Report Share Posted October 16, 2008 glass will be alot stronger in the way of bowing in every direction than plywood. i expect the joins of the ends, where the plywood is glued & screwed together will pull away very quickly because of the bowing. the plywood tanks i have seen were all fitted in between steel frames which were the tank, the plywood was simply the infilled walls for fibreglassing onto. Quote Link to comment Share on other sites More sharing options...
Olly Posted October 16, 2008 Author Report Share Posted October 16, 2008 the plywood would be on the inside of the tank with fibreglass over it, and a veneer or maybe a thin tongue and groove type wood on the outside. I have the building skills to make it strong enough and look decent, just need some time to start putting it together Quote Link to comment Share on other sites More sharing options...
smidey Posted October 16, 2008 Report Share Posted October 16, 2008 the plywood would be on the inside of the tank with fibreglass over it, and a veneer or maybe a thin tongue and groove type wood on the outside. I have the building skills to make it strong enough and look decent, just need some time to start putting it together take it from a cabinet maker. it will bow & that will create point loads & that will make it pull itself apart. its not rigid enough in the centre of the panels, glass is very rigid & still bows. to make it you will need to make the plywood box & fibreglass the inside to seal it, when it bows the fibreglass will crack & begin to leak. Quote Link to comment Share on other sites More sharing options...
Olly Posted October 16, 2008 Author Report Share Posted October 16, 2008 the plywood will be braced by 100x50 laid on edge about 200mm apart. As a joiner can you tell me if that will be strong enough? here is an example of what a panel will be like: Quote Link to comment Share on other sites More sharing options...
smidey Posted October 16, 2008 Report Share Posted October 16, 2008 the plywood will be braced by 100x50 laid on edge about 200mm apart. As a joiner can you tell me if that will be strong enough? here is an example of what a panel will be like: i don't believe it will as it will only be a strong as the fixings at either end of the bracing. the weak point will be at the corners especially, i would use aluminium angle for holding the corner together but it won't be to pretty & will end up costing similar to a glass tank & add heaps of time to complete it. I would personally only make a plywood tank if it was 2 or 3 times that size & it had a steel frame to fix to. give it a go but i dont think it would last more than 12 months. Quote Link to comment Share on other sites More sharing options...
richms Posted October 16, 2008 Report Share Posted October 16, 2008 I would go concrete before I would consider wood for a tank, and even then it would be something built in-situ so becoming a permanant part of the house rather then a portable tank like you are describing. Glass is a cheap, reliable proven method of making tanks, why do you want to stray from it? Quote Link to comment Share on other sites More sharing options...
Olly Posted October 16, 2008 Author Report Share Posted October 16, 2008 i don't believe it will as it will only be a strong as the fixings at either end of the bracing. the weak point will be at the corners especially, i would use aluminium angle for holding the corner together but it won't be to pretty & will end up costing similar to a glass tank & add heaps of time to complete it. I would personally only make a plywood tank if it was 2 or 3 times that size & it had a steel frame to fix to. give it a go but i dont think it would last more than 12 months. I agree the weakpoint is the corners. To counter this, I plan to put a 100x100 post in each corner. There will be an aluminium plate (blue) that will be bolted to the horizontal rail and back through the corner post (bolts in black). this will mean that the forces should be transferred into a tensile force along the length of each horizontal beam. Thanks for you're help Smidey, this is why I posted this before getting started - to see what people think will work and what wont Quote Link to comment Share on other sites More sharing options...
ryanjury Posted October 16, 2008 Report Share Posted October 16, 2008 Personally I still think its dicey and going to be alot of work and probably not going to be better than a glass one.. But you're determined to give it a go It would be a good project if you have the time/skills/tools and money to do it. lol not to mention your own house to fill it up in so your parents/landlords don't flip when it explodes.. However to help you out ive found some articles http://www.cichlid-forum.com/articles/d ... uarium.php http://www.cichlid-forum.com/articles/d ... arium3.php http://www.cichlid-forum.com/articles/d ... arium2.php Obviously they're american sites and some of the advice re materials and costings etc will be wrong but design ideas should be a good place to start.. Quote Link to comment Share on other sites More sharing options...
Olly Posted October 16, 2008 Author Report Share Posted October 16, 2008 Personally I still think its dicey and going to be alot of work and probably not going to be better than a glass one.. what dont you like about it? thanks for the articles I hadnt seen the third one Quote Link to comment Share on other sites More sharing options...
cpk Posted October 17, 2008 Report Share Posted October 17, 2008 Hi olly you should listen to the cabintmaker he will know his stuff.Absolutely no offence intended here but why reinvent the wheel Quote Link to comment Share on other sites More sharing options...
kiwipete Posted October 17, 2008 Report Share Posted October 17, 2008 Why not use a glass tank and sit it in a plywood box to look like it is a ply tank? Quote Link to comment Share on other sites More sharing options...
lmsmith Posted October 17, 2008 Report Share Posted October 17, 2008 Why not use a glass tank and sit it in a plywood box to look like it is a ply tank? I think his aim is to make it cheaper, not just for the look of the ply... Quote Link to comment Share on other sites More sharing options...
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