Backyard Aquaponics
A place to discuss aquaponics

That's the way I'd go Stuart.... not sure of your dimensions... but looks to be a standard 12m long table... even with 10 trays, that's about 2mtr wide...and about 80l\L+ of flow... a small pond pump should do the job...

I use these... JHQ-2000....1400ltr/hr... cheap, reliable (continuous) and very quiet ....
http://www.aquariumproducts.com.au/subm ... _pumps.php

Are you still intending to have multiple flood & drain growbeds (flooded sequentially) or are you know going to just have two long DWC style growbeds with floating rafts?

Two long GBs that were theoretically going to be each equal to the volume of the FT ie around 8000L. Due to the slope of the ground and the fact that I can't be bothered digging them out (I don't have an earth moving MIL unfortunately) they will be substantially less than this.

Very frustrating day to day.

Every time I try and get anything done it starts raining. Which is a good thing but it means that all the stuff I have to get done outside is not getting tackled.

Consequently not much progress but here is the frame of the FT finished (mostly)

What is the fish tank going to be built of?

Cool room panels around the walls on the outside edge of the GH and the internal FT GH wall made up of gutter rooffing (has an E cross section) as shown. THen after I add a wooden edge around the top the created box will be lined with old carpet, lined with pond liner and filled with water.

In further answer to the cost of the GH. I got the basic frame free but their was a bunch of clamps and pipes missing. So I've spent about $200 an clamps and pipe to complete the thing. However I'm about to spend another $150 on clamps and maybe $150 on pipe for a bunch of diagonal bracing.

See this thread if you have any suggestions on what I should be doing regards diagonal bracing

viewtopic.php?f=8&t=3973&p=142609#p142609

Stuart,
Just a little warning (hoping you already thought of it though) that a rectangular above ground water tank is really going to try and bow out at the sides. My galvanized waterfall tank on my system that is only 8' long, 30" wide and 24" tall that I braced around the top with lumber, is buckling out pretty badly. The lumber is bowing quite a lot and the tank wall has buckled even more.

I don't want your fish tank to collapse out on you unless you are planning on getting a video of kayaking through your greenhouse.

Water is heavy stuff.

TCLynx Yep it is but I think I'm using different materials to you. Firtst the cool room panels are "stressed skin panels*" which are really strong and the gal is the gutter rooffing** with a cross section in the shap of an "E". I think form the picture that the gal your using is sheet or at least almost so.

*Stressed skin panels are two sheets that have a high tensile strength seperated by a layer that has a high compression strength. Jumbo floors for example are two skins of aluminum seperated by a wafer of balsa wood with the grain running from skin to skin which spans the whole width of the aeroplane with minimal support. Ie spans of 9m or more from a composite material only a few inches thick.

** http://backyardaquaponics.com/forum/vie ... hydroponic this link shows a tank made from a similar gal tin sheet that I am using.

Just hammer some star pickets in around the edge to be sure - its going to be a lot of water pushing outwards.

I guess I'm not so worried about the panels themselves but what is supporting them. That is a long flat section. I fear a few fence posts may not be good enough. Anyway, a heads up is all I was meaning, I expect you will take a close look and do what you need to do.

How have other people gone with such lined boxes?

I've got a spacing of a starpicket every 1.2m and the bottom of the tin is set into the ground from between 2" to 6".

Has anyone done similar and had it fail?

My thinking is that for the sides to fail the E section tin would have to rip and given the tensile strength of the metal I thought this unlikely. If I had it around the other way the vanes of the tin could crumple relatively easily.

IF you think it under engineered how would you fix it? More star pickets or some sort of beam along the bottom?

I don't know what these starpickets are so I can't really say if they would be enough. My lined tank is mostly in the ground. The monster grow bed is partly in ground but it definitely bulged the lumber out where I didn't have enough stakes holding it in.

Perhaps look at how they do above ground swimming pools. The curved or round ones are easy but the oblong pools that have a flat section on either side use pretty sturdy supports to keep the pool from busting out.

Good luck.

S, are you able to tie the starpickets together over the top of the pond?

My mega sump hasnt, and wont fail, but has spread outwards.

TCL these are star pickets...

I have star pickets around my compost heap with roof sheeting (the ribbed stuff) on the inside. It is only 1m cubed in size and it pushes the star pickets out a bit. The surface area of the star picket holding the wall would also be very small. Wouldn't that mean much greater pressure against the star picket. I would say with the water you plan to put in there you will need more support.

I have checked out the link you have added and those supports are very big (thick) and I would say would be deep in the ground and cemented in. The height of the wall would also play a role. The pictures of the support on the link looks to be only about a metre high, if that. Anything higher than that would surely cause further issues.

I am no builder but would suggest 2/3 of the support would need to be under the ground.