Alrighty, enough of these piddly little tanks. Its time for my fish to have their own private lake!
This was also to be an experiment in aquaponics as a filter system for the fish. I'm still trying to create a system that requires practically no attention other than feeding.
I wanted a tank that would sit in the corner and have an 8 foot viewing window. So the base started out with a 6' side wall, a 7' back wall and a 2' wall for the grow bed to return to. It had to be pretty skookum as it would be supporting well over a ton of water and media. The corner of my basement already had a ledge to place the side and back wall on so I only required 9 2x4 legs that I figured would be supporting 150lbs each. Nothing was placed over 2' apart.
All framing joints were screw and glue. Support legs were mortise and tenon. Plywood walls were screw and glue at 6" apart. The top cross braces were glued dovetail joints.
Labour time: about 60 hours.
Cost of materials: about $1200.00 CAD.
Volume of tank: 300 gallons US (330 max.)
Weight of water: 2500 lbs (2750 max.)
Gravel weight: 100 lbs (grow bed not included)
River rock weight: 300 lbs
Total weight (not including plants, pumps, filters, wood, glass or fish): 2900 lbs!
Not the kind of tank you would want upstairs.
It must be noted here that this tank had the extra inconvenience of being built indoors, the size and location meant that the tank would never be able to be moved and all construction dust and smells of curing fiberglass would have to be tolerated by all in the house. A futher addition to the discomfort to this was the fact that a rat had found its way into the walls of our humble abode and added its rotting corpse to the smell. We were not pleased!
Once all the woodwork was completed I used automotive body filler to fill all screw holes and smooth the plywood surface. During the fiberglassing process I positioned 1/2" blocks with a chamfer on them into the glass where the main windows would be going, this gives the windows something to sit on as the fiberglass material in the corners is usually not square. As I was being a bit cheap on the fibreglass and using polyester resin, I had to use a gelcoat to prevent moisture seeping through. The cross braces of the top were dadoed to fit glass panels. The side and front glass was scavanged from a 55 gallon tank I had purchased, it was cheaper to buy a whole tank than to buy just the front glass.
The fiberglass was allowed to cure for 3 weeks before putting water in and water was circulated through the system for a month prior to draining and refilling to add life. This circulation was done through bags of activated carbon material in order to remove any toxins leeching out of the fiberglass.
Doing some final adjustments with the flow, yes the piranha are in there. They use genetically modified ones in the movies, real ones are nothing to worry about.
Oh yeah, 300 gallon mark!
Finally got the skirt finished. I used the river rock that I removed from the tank. The rock was removed as it made it difficult to keep the tank clean.
This was constructed of plywood with the same fiberglass treatment as the tank. Dimensions are 2' x 4' x 5" depth (only using 2.5" of gravel at the moment). It is a constant drain system which means that water flows through constantly rather than doing a "fill and flush". Built on a slight angle, water flows in the top end and flows back into the tank through a slot in the base of the other end. A grid of 3/4 PVC keeps the flow from slowing down if the gravel starts to become clogged (that's my theory anyway). Capillary action keeps the gravel moist just under the surface and the heat from the lights acts to help heat the water taking some of the load off the heaters while giving the growth benefits.
The garden after 1 1/2 months of growing (lettuce from seed). I have been thinning out the lettuce crop for the past week, way too crowded in there.
After 3 months in operation it seems that my plumbing idea isn't as effective as I had hoped in helping drainage after things started to clog with fish waste. This is the 3rd crop of lettuce. It also appears that this small garden space is not able to keep up with nitrate removal, as well as I had hoped, for a tank this size and I have had to turn up the drip system to help keep levels down. This was mandatory as I was starting to suffer fish loss although I'm not really sure why as tests seemed to be within livable parameters.
I'm not sure what to do about the "pooling" in the garden but will have to figure something out as I'm sure this will not have any good effects on the plants growing in this much water. The other end is still good, but for how long I don't know.
I have built a new grow bed that cures the flood problem and seems to work better for both the plants and fish. This bed is a full 12" deep and houses 3/4" gravel (approx 1000 lbs) instead of the pea gravel that clogs up.
Being deeper I opted for a fill and flush system using a bell valve so the main tank fluctuates in volume from 330 to around 315 gallons depending on how full the bed is at the time.