Fish Tank OOPS

We tested the fish tank after installing it in the greenhouse.  It failed when the water was just beginning to drain.  My son repaired the tear and erected concrete forms around the perimeter of the platform.  Then he put the mended fish tank in place and began to slowly fill it with water, pouring concrete into the space between the form and the fish tank at the same rate as it filled with water.  As a result, the outer concrete shell fits like a glove to the inner tank and there is no visible bulging or distortion from concrete or water.  He stopped at 16" since the upper 1/3 of the tank receives far less pressure than the bottom 2/3.This is a closeup of the interior, showing one of the tension rods and the 1" gluing strip along the bottom.  So far the tank has proven to be sturdy and water-tight.
Here are pictures of the inside insulation of my greenhouse with the ends of the legs of the tables that will support my grow tanks.  I daubed on silicone to form waterproof sleeves 2" up the legs.

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Construction of Fish Tank

I had a lot of square aluminum tubing on hand.  I only put it at the corners for the sake of being pretty.

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Fish Tank Fail Or OOPS!

I should have a fish tank that will be the equivalent of my grow bins to give the fish enough room and handle the exchange of nutrients efficiently.  So far I have planned for a little more than 200 gallons worth of grow bins and planting tubes.  The commercially available tanks take up too much room or are too expensive, or both.  If I build a strong wooden box that is 2 x 2 by 8 it will have well over 200 gallons in capacity and it will fit neatly in my greenhouse.  Fish pool liner and wood for the pool would come to under $100.  Since I dont have to deal with outdoor conditions, cattle (as in a stock tank which is built to withstand large animals), or other similar conditions, it seems the best solution to my need for a large tank.

We installed the fish tank, plumbed the grow bins and decided to do a water test before adding gravel or chemicals.  The grow bins each consist of three 27 gallon bins connected with ABS pipe with the bell syphon installed at one end of one of the bins.  The sump is an old porcelain/cast iron bath tub.  I have a 550 gph pump.  The cycle went beautifully from the first in one set of bins and required only a little tweaking in the second set of bins to work as well.  Meanwhile we were filling the fish tank.  It had reached the point of beginning to drain when we heard a little popping noise then a wave of water ripped the side of the fish tank as over 200 gallons gushed across the greenhouse floor.  It immersed the electrical cord connection but fortunately it was on a breaker and immediately cut out before we could be electrocuted. 
We quickly discussed what could be done as the greenhouse slowly drained.  We purchased concrete mix, chipboard for forms and reinforcing mesh.  Today we will mend the side of the fish tank, create walls of concrete to contain what is now  liner.  None of the joints of the fish tank failed.  It was a simple failure of the material.  With concrete walls to provide the resistance to pressure we should be back in business again and ready to add gravel to our grow bins.

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Bell Syphons in joined bins working fine

On the same day that we discovered the problem with the fish tank which has been rectified in the intervening week, we ran water into the joined bins that make up two grow tanks.  Three 27 gallon bins were joined with ABS pipe as a consolidated grow tank, draining with one bell syphon.  We made two sets and each performed very well.  Now that the fish tank is stable we are going ahead with adding expanded shale to the grow bins.  I have some seedlings growing in vermiculite in preparation for transplantation into the grow tanks.

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