Plastic Deck Lumber for Fish Tank Frame

[B. Pearcy]

Do you think the plastic lumber will work for a pond liner frame? How many gallons do you think it will support?

[LogicalHydro]

Do you mean like a composite such as Trex?

[TCLynx]

That plastic or composite decking is not as sturdy as wood, as in it is rather flexible.  When using it to replace existing decking, I got a bit of a shock that I had to space the joists closer together to be able to use it for decking when I replaced the deck in my grandmas house.

 

This flexibility can be used to advantage if you want to make curved raised beds but it might not be helpful if you are trying to make rectangular grow beds as they will want to bulge out and the plastic decking won't be much help to stop it unless you use liner that is strong enough to support a radius on the bottom corners so it will pull down rather than push out (but that only works for raft beds, not gravel.)

 

Or are you talking fish tank?  In which case I would say go round and use cattle panel as that will be much cheaper than plastic lumber.

[B. Pearcy]

TC,

I got the idea while looking at Cosmo's fish tank today in the greenhouse during the tour.  I am struggling with having something that looks presentable in my backyard. 

I noticed Cosmo's fish tank appears to be wooden with a pond liner.  It's pretty good size and appears to be working well. I remember you saying previously that wood is susceptible to termites here in FL, so I thought about the plastic decking as an alternative. It actually looks pretty good at the local state parks where I see it often

 

Brian.

[B. Pearcy]

I was think of the composite like ForeverDeck or similar.  I am trying to think of something resistant to termites, but still sturdy enough to hold a pond liner.

LogicalHydro said:

Do you mean like a composite such as Trex?

[B. Pearcy]

Here's a link to a koi pond built with plastic deck lumber. I of course would be building something much smaller and with much simpler filtering design, but this is basic the idea I'm thinking of.

I guess the question is how deep you have to dig to get proper support for the sides. They dug this one pretty deep. I do like the looks of it alot. With less water, I'm wondering if you could get a way with only 2 feet of in ground digging.

(I got this basic idea at Sahib's and at Cosmo's today during the tour.)

[LogicalHydro]

Not only termites but it will resist rot very well. TC is right though. Composite is very flexible, but weak compared to real wood. But with proper support I think it will work great. A smaller tank than the one shown should be attainable.

[B. Pearcy]

Maybe I should use some painted rebar for support every 2 feet or so.

LogicalHydro said:

Not only termites but it will resist rot very well. TC is right though. Composite is very flexible, but weak compared to real wood. But with proper support I think it will work great. A smaller tank than the one shown should be attainable.

[LogicalHydro]

It's all based on depth and not horizontal area when figuring water load. So it depends on size to properly develop a cost to support ratio.

[TCLynx]

an option, if you go round, the shape gives strength.  See flat sides will tend to bow out but a round tank properly tied together could be dressed with anything pretty (those bamboo shades or whatever.) and be quite strong with nothing more than fencing and a little pond liner and tarp or insulation board.  But if you go rectangular, you need to think about bracing.

 

Now this could probably be done if you use the lumber in the proper way.  Think of the walls of the tank like stud walls.  you would need to put some of the lumber sideways to the pressure.  I don't know the particular brand of plastic lumber you mention though or how easy it is to work with or screw together.

 

Cosmo's fish tanks have wood frames but they use concrete board instead of plywood.

 

(truth is after all this, I expect you may find you would spend as much as on an oxbow system in the end.  You might save some trouble simply by having Jon and Cat install one for you and offer their support through cycle up too.)

 

However, if you really have the spirit of DIY in you.  I'd love to see something built as you are suggesting, sounds kinda cool.  And that koi pond looks really pretty but I don't expect building that way will save any money.

[B. Pearcy]

TC,

 

I'm trying to visualize the cattle panels, but I don't have a good idea of how those would be used. You're very right. They would be much cheaper.

I love the Oxbow, but my wife vetoed the price already when she saw it over my shoulder (lol). It would be perfect though.

TCLynx said:

That plastic or composite decking is not as sturdy as wood, as in it is rather flexible.  When using it to replace existing decking, I got a bit of a shock that I had to space the joists closer together to be able to use it for decking when I replaced the deck in my grandmas house.

 

This flexibility can be used to advantage if you want to make curved raised beds but it might not be helpful if you are trying to make rectangular grow beds as they will want to bulge out and the plastic decking won't be much help to stop it unless you use liner that is strong enough to support a radius on the bottom corners so it will pull down rather than push out (but that only works for raft beds, not gravel.)

 

Or are you talking fish tank?  In which case I would say go round and use cattle panel as that will be much cheaper than plastic lumber.

[Sahib Punjabi]

Wow! You do seem to like the Plastic Deck Lumber...now do you have shares in the company making such ?...hahaha

 

I love the link for the making of the Koi Ponds. If you note, they appear to have finished the outside with rock (as I have done on my home Koi ponds). For a "cheap and cheerful" solution, may I suggest that you buy a 300 gal + Rubbermaid tank for some place like Tractor supply (around $250 budget), dig that in 2 ft if you want it sunken and want both thermal protection in winter as well as water weight support for the sides, build a frame and use "Plastic Deck Lumber" for the outside...your choice of color (price of decking your call). Now you should be able to have a fish tank that is "a little less obvious to the neighbors" and one that you can experiment with for some time before you are ready to buy the ultimate (yes I too love that system but my wife also was rather strong with her veto), Oxbow

 

God bless

 

 

[TCLynx]

You could probably do the whole system from stock tanks and skirt it all with the plastic lumber or bamboo screening to make it pretty.