Tilapia in Isolated Stock Tank

[Ryan Rogers]

Sylvia - thanks for the invite to the group and for pointing me to the Gator Farm for tilapia fingerlings. I've emailed them and am waiting for their response.

 

I wanted run my plan for tilapia by everyone and see if anyone had any suggestions. I recently built a 12x16 greenhouse up at 7600 feet in Evergreen, CO, in which I will grow vegetables in soil (seeds
started sprouting today!) . In this greenhouse I have placed a 100 gallon black
stock tank that I picked up at a garage sale for $10. The main reason I put it
in the greenhouse was for thermal mass, but also want to experiment with growing
out fingerling tilapia for the table/freezer. Obviously I'll need to heat it,
but that's okay because the heat will just escape into the greenhouse which will
need it anyways. For aeration I planned on just doing an air pump with airstone.
I'll probably feed commercial (Aquamax?), with the occasional vegetable scrap
tossed in. Maybe I'll grow some duckweed on the side as well...

 

My main question is about filtration - since this is a "closed tank" and not tied into a hydroponic system (not yet!), my plan was to drain water out the bottom spigot daily, individually fertilizing my plants
in the greenhouse. Will this approach be enough to keep the water quality good
enough for the tilapia, or do I need an actual filtration system? If it would
work, how much should I drain off on a daily basis (10%? 25%?).

 

Is there anything else I would need to do to "treat" the water for tilapia? I'm on a well, which was recently tested and is good water (for people at least)...

 

Finally, in terms of density, if I followed the 1/4 lb fish per gallon rule, and planned to grow them out to 1 lb (that is normal harvest weight, right?), then I should probably only put in 25 fingerlings,
correct? Any way I can up that density without jeopardizing the
fish?

 

Anything else I'm forgetting?

 

Thanks for everyone's input!

[Sylvia Bernstein]

Great discussion! Boy, I learn new things every time I come in here and "listen" to you guys. Ryan, out of curiosity, when are you going to hook up plants to your new tilapia tanks? Will make your life a whole lot easier....

[Ryan Rogers]

Unfortunately I think the whole system is gonna have to wait until next season. Now that I know what's involved in getting fish tank operating properly, I realize it's just not in the budget right now - I've already gone way over on building the greenhouse! Besides, I already have a lot to experiment with and grow in all my soil beds.

Next year, however, I see a true aquaponic system happening....

[David Hart]

Heres a link to someone building their own biofilter. I based mine 'somewhat' on this design. He uses a venturi to add air. I just ran an airline from my pump...added a few airstones in the bottom.
This has lots of pictures....hope it gives some ideas.
http://leisure.prior-it.co.uk/build-diy-pond-bio-filter.shtml

I run my water through a solids seperator 'before' going into the biofilter.

[Richard Wyman]

Ryan, I made a filter from a couple of buckets, they drain down from the top. For a first season crop of fish I bet it would work with maybe just a little more maintenence than a bottom filling one. I spent a total of about $9.50 to make the one I have. A standpipe can prevent overflows in case of media clogging. You just have to check it occasionally. A sock and some filter fiber at the top catch most of the solids. One of the lids is the diffuser.

You could always use a cheaply made filter this year and do it up nice and proper next year after the budget is back in line.

Ryan Rogers said:

Unfortunately I think the whole system is gonna have to wait until next season. Now that I know what's involved in getting fish tank operating properly, I realize it's just not in the budget right now - I've already gone way over on building the greenhouse! Besides, I already have a lot to experiment with and grow in all my soil beds.

Next year, however, I see a true aquaponic system happening....