Backyard Aquaponics
A place to discuss aquaponics

Doug, whats happening? Give us an update?

Things have stabilized. The 150 blue gill are doing fine (eating like pirahna!). That is not enough fish to fertilize my 92 sq ft of grow bed. I have to top feed with fish & seaweed emulsion. I have 10ppm nitrate, but no phosphate or potassium reading. Ammonia & nitrite are still 0.0. The pool filter I added to the system is closed circuit with fish tank. It moves a lot of water thru the zeolite in the filter (220vac high capacity pump thru 1.5" hose). There is no more buildup of fish waste on the bottom of the tank. I added an exhaust fan thru the wall to control humidity more than temperature. Now I am designing and building controls for the filter pump, exhaust fan, vents, heat exchanger pump, and water circulation pumps (to biofilter and grow beds. The references from Michael F were excellent and helped me evaluate what was happening in my system.
The concrete and tank water is doing an excellent job of regulating greenhouse temperature. Today it was 97F outside and 88F inside max. I did not use any fans to do this. Natural convection thru the vents and thermal mass did this. I am pleased with the temperature swings in the greenhouse.

Am I long winded or what???

That's great news DB...keep updating more regularly

Did you figure out the cause for your losses then?

You can measure phosphate and potassium? What are you using? I also feel like I don't have enough of those two, but have so much nitrate it is ridiculous.

Janet, I have a phosphate test kit from AZOO. The potassium is a guess based on plant leaf symptoms and Dr. Savidov's comments in the SRAC documents in Michael F's links. It appears that needing extra potassium in Aquaponics is common (not enough in the feed). It is desirable to use potassium hydroxide to counter acidity. My highly alkaline system can not. There is potassium biphosphate which has a pH of about 4.6 for me. This costs about a dollar a pound in 50 lb quantity.

LKB, I have been swamped with work and posting suffers. I will try to post more often.

John, I am guessing at all of this, but it is my best guess. The first losses of hybrid stripped bass and perch and some hybrid blue gill appeared to be the leeching from the new concrete. The fish biologist at Jones fish hatchery agrees. He said the bass are quite sensitive. That ended without losing a single catfish. The catfish and blue gill were eating a lot and creating a lot of fish waste. My slow pumping to the bio filter was not pulling the waste out of the fish tank and it was building up as lots of particles in the water and a sludge on the bottom which smelled very anaerobic. I knew I had a problem and started renovating a 23+ year old pool sand filter from the barn's semi precious scrap pile. I plumbed it and used zeolite rather than sand in the filter (zeolite filters to 0.3 micron & sand to 3 micron) zeolite also pulls out heavy metals and ammonia (sometimes used in aquarium filters, but I used 50 lbs). It took 5 days to get it working. Meanwhile the catfish are bottom dwellers, so they were in the sludge. I think they were streesed and with low immunity developed a disease. It was a very bad disease because evryone of them died with no blue gill losses. At this point I have about 150 blue gill, 1 perch, and 1 bass (so I really have three kinds of fish and still have a perch harvest to look forward to ). The pool filter is a 220vac, powerful pump that moves lots of water in a closed circuit from/to the fish tank. When it is on, it really stirs up the water and pulls out the waste. No more sludge and only a small amount of particles in the water. Now I am installing computer control of the pump. It draws a lot of power (not what I want), so running the pump two or three hours a day is what I hope is effective. Perhaps timed to 2-3 hours after each feeding run the pump for 90 minutes?? Last two days I pulled out one dead catfish in morning. With 3000 gallons to mingle with the blue gill, I guess I missed seeing them in there, but the disease does not miss them. I am going to investigate where I can get fish diagnosed when they die of a disease/parasite. Maybe University of Michigan or Michigan State University. Then find out how to get the fish to them in a state they can evaluate (frozen, formalin, alcohol??).

This is all good news and good findings Doug. Keep up the good reports. I bet your woes are overwith and the bluegill will be your prime stock as a hardier fish than the bass or cats.

In your previous post you expressed your thought that 150 Bluegill would not be enough for 92 sq ft. of GB space. With 3,000 gallons / 92 sq. ft. of GB space that is a low ratio indeed. A densely stocked 3,000 gallons could support an entire commercial greenhouse. Therefore dillution will be your challenge versus stocking density. Your 3,000 gallons has to be cycled through the GB's to get those 150 bluegill's waste cycled completely.

Thanks for the update Doug, here's hoping for fat fish.

just a question on zeolite, does it disolve like calcium carbonate ?

and if it removes amonia wont it be detrimental to the system, i mean no amonia means no bacteria and that means no plants .. or did i miss something

either way im glad to hear that you got a solution in place to stop you losing anymore fish

Cheers

delgrade, good point on the zeolite absorbing ammonia. I did not need that function, but I did need the 10 times better particle filtering. My idea on ammonia is that the zeolite filter only runs 3 hours per day in closed loop with fish tank. The 10gpm pump going to the biofilter is 24/7. I am hoping 3 hours of ammonia absorption will be OK. My ammonia levels are 0.0 without the zeolite, but there must be some for the bacteria. I have reduced it less than 3/24 or 1/8th I would think. It does not dissolve appreciably and its ability to absorb ammonia decreases with age. There is a process of purging the ammonia from the zeolite to renew its ability. I will not do that. I just backflush it when it fills with particles (indicated by a back pressure guage).

Watch for deficiencies showing up in your plants Doug....

There's at least circumstantial evidence to suggest that removal of solids from an AP system removes a large percentage of minerals and trace elements otherwise available... particularly Potassium.....

Rupert, I have deficiencies and the plants show it. My fish/plant ratio is way off and I did several large water changes to combat my fish losses. My 3000 gallons has only 150 of 60 gram blue gills. The feeding is only 160 grams per day for 92 sq ft of growbed. I do top feeding of plants with fish & seaweed emulsion. Long range, I will get more fish and these will grow.

The solids may be in the system for some time. The zeolite filter only gets backwashed once a week. So when I run it 3 hours per day, the mnerals have a chance to dissolve in the water running thru the filter.

I do have potassium deficiency as do many aquaponics systems (not enough potassium in feed) per Dr. Racocy in SRAC documents in Michael Ferrini's links above.
http://srac.tamu.edu/tmppdfs/331916-451 ... e3164b513c

http://srac.tamu.edu/tmppdfs/331916-452 ... e3164b513c

Many use potassium hydroxide to raise pH and that helps. My system is too alkaline, so I need to use an acidic source (perhaps potassium biphosphate). My top feeding helps my plants for the moment.

You're on the ball Doug....like that fish and seaweed emulsion stuff

Doug,

How long have you been running your sand/zeolite filter? I am still running sand in mine, and I find it clogs and requires way to much back washing. I don't know how you could run yours with zeolite for very long with out cloging. Just curious, I understand you had a problem with the fish... but why would it need to be filtered so fine? Just an extra precaution? If so I guess I understand, however, You find it cheaper to just vaccum (to waste) the bottom when it accumulates. If you have potentially toxic gunk at the bottom, you don't really want to stir it up do you?

I ran into a similar problem one time and lost a few fish. I tried a few different things, and for me, getting the gunk out with the least mixing really helped.

Just a few thoughts from my experience.

Mathew

are you sure you need such fine filtering ? 0.3 of a micron is gettin bloody, small actualy thinkin about it the sand you were using is quite fine as well i would have thought that sand would filter down to about 10 microns or so

still if its working i guess thats the main thing

i w as goin to sugest trying a venturi to suck some of the muck up from the bottom and then dispalcing it into the grow bed bed (no waste ) but your running NFT or DWC so that might not work

CHeers