Aquaponic Gardening

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This is the place for comments on and any discussion of the "Rules of Thumb" document on the home page.

I can't promise that I'll make suggested changes - this has been through some strong vetting already - but I'm certainly open to hearing your thoughts and suggestions...or maybe just sharing that you find it useful!

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Sounds like you got both good and bad news, Sheryl. Yes, high pH will stop cycling. It also turns ammonia into ammonium which is very bad for the fish...if you have fish in there (i.e. not using fishless cycling). If you don't have fish you can take the pH down quickly, but if you do, do a partial water exchange then take the pH down gradually - aim for no more than a .2 movement a day. Good luck.
If your source water is the reason for the really high pH, I recommend putting the source water in a large container that you can add a bubbler to. Then adjust that water with acid down to the pH range you desire. This might take a couple days to actually get it adjusted and stable before you use it to do the water changes on a system that has fish in it.
Good stuff. Really nice to have this much information in one place.
Hello Sylvia 18 degree celsius is 68 degree fahrenheit Dr James E. Rakocy rot in his book that the bacteri is daeing
below 18 degree celsius and hi is the expert in agrculture
manfred
I know cooler water slows down the bacteria but I grow channel catfish and they are still eating well down to about 65 F water and that doesn't cause me to have ammonia or nitrite spikes from my bacteria dieing off. People raising trout definitely manage Aquaponics in cool water so there has to be some bio-filter bacteria out there that function just fine below 68 F. Now if you were in a tropical place and the bacteria that colonize your system are suited to the more stable climate and the temp suddenly drops, that might be different.
In situations where the water warms and cools slowly, there is usually time for the bacteria to ramp up and down along with the fish feeding rates. Now once the water gets below 50 F, I would not be feeding since most fish wouldn't be eating anyway and the bacteria have definitely chilled out and a sudden return to higher temps will need to be accompanied by a slow ramp up of feeding so one does not get ahead of the bacteria re-populating.


Manfred Wille said:
Hello Sylvia 18 degree celsius is 68 degree fahrenheit Dr James E. Rakocy rot in his book that the bacteri is daeing
below 18 degree celsius and hi is the expert in agrculture
manfred
I have to second what TCLynx says here - my system is exactly at 68 degrees and something is working, because I've somehow moved past the ammonia spike and nitrite spike and have a decent bunch of nitrate.

For what it's worth, I didn't bother washing my gravel, just put it in as it was. My system uses constant pumping and a bell siphon that goes off every 10 minutes. Anyway, water was completely clear a week later.

Meg



TCLynx said:
I know cooler water slows down the bacteria but I grow channel catfish and they are still eating well down to about 65 F water and that doesn't cause me to have ammonia or nitrite spikes from my bacteria dieing off. People raising trout definitely manage Aquaponics in cool water so there has to be some bio-filter bacteria out there that function just fine below 68 F. Now if you were in a tropical place and the bacteria that colonize your system are suited to the more stable climate and the temp suddenly drops, that might be different.
In situations where the water warms and cools slowly, there is usually time for the bacteria to ramp up and down along with the fish feeding rates. Now once the water gets below 50 F, I would not be feeding since most fish wouldn't be eating anyway and the bacteria have definitely chilled out and a sudden return to higher temps will need to be accompanied by a slow ramp up of feeding so one does not get ahead of the bacteria re-populating.


Manfred Wille said:
Hello Sylvia 18 degree celsius is 68 degree fahrenheit Dr James E. Rakocy rot in his book that the bacteri is daeing
below 18 degree celsius and hi is the expert in agrculture
manfred
I'm with Meg and TC here, Manfred. You may have misunderstood Dr. Rakocy. Nitrifying bacteria will survive to freezing temperatures although, as TC pointed out, it doesn't thrive and multiply below a temperature above freezing (I'm not sure exactly what temp that is). It is just like fish and plants in that respect - there is a broader range of temperature at which it thrives and multiplies (i.e. procreates or puts off fruit) than the range at which it merely survives. I have a friend here in Colorado who successfully grew trout in a 300 gallon tank outside last winter. He partially sunk the tank into the ground, added aeration and a pond heater to keep a hole in the ice, then filtered through a media bed with no plants. Had gorgeous trout to smoke in April.

Also remember that Dr. Rakocy worked with a very different system than the 12" deep media beds that we are talking about here, and in a climate that was very temperate year round.
I would hesitate to give a specific density of planting per x of something else but if the raft systems give a number of some type of plants per some amount of fish load, I would expect that a system where the solids are left in the system, you should be able to support at least as much plants if not way more since the solids remaining in the system will provide more nutrients though it might take some system maturity before the mineralization of the solids really benefits the plants much.
Interesting idea, Fishy One, but I'm afraid I'm with TC on this one. Just too many factors to consider - fruiting vs non-fruiting, particular variety, age, sun angle, maturity of the media bed. One of the real benefits of a media be is the total flexibility you have with planting a wide variety of plants...then moving them around if you need more room after a while.

I added the line "You can place your plants roughly twice as closely together as you would in soil". I know it's not quite what you were looking for...but it is something :)
I have a quick question about the rules of thumb - Is there a minimum water depth for fish tanks? I see that the grow beds need to be 12 inches, but I am not sure about the fish tank. I am thinking about raising tilapia or catfish and I am gearing up to start a small system. Most of the tanks I have found seem to be quite shallow. I think I read somewhere that you want a tank that is a least three feet deep, but I have seen lots of shorter tanks and small ponds that are very shallow.
Would a rubbermaid tank that is 25 inches work for fish tank? For example: http://www.rubbermaidforless.com/rubbermaid-4247-gallon-capacity-li...
FWIW, I'm starting with a 100 gallon Rubbermaid tank. The Murray Hallam systems clearly have tanks that are pretty shallow (the lids to his original home-based systems are short enough to serve as seating when you gather for fish barbeque). And with the DIY bathtub systems, the water can't be deeper than a bathtub.

With the new CHOP2 concept, you no longer need a fish tank that is taller than your growbeds, even.

David Lindemann said:
I have a quick question about the rules of thumb - Is there a minimum water depth for fish tanks? I see that the grow beds need to be 12 inches, but I am not sure about the fish tank. I am thinking about raising tilapia or catfish and I am gearing up to start a small system. Most of the tanks I have found seem to be quite shallow. I think I read somewhere that you want a tank that is a least three feet deep, but I have seen lots of shorter tanks and small ponds that are very shallow.
Would a rubbermaid tank that is 25 inches work for fish tank? For example: http://www.rubbermaidforless.com/rubbermaid-4247-gallon-capacity-li...
The "rule" I've always worked with for tank depth is a minimum of 18". Meg is right - Murray is now doing bathtubs that aren't more than 18" deep. 3' would be better, for sure, but I think you are fine with what you are planning.


David Lindemann said:
I have a quick question about the rules of thumb - Is there a minimum water depth for fish tanks? I see that the grow beds need to be 12 inches, but I am not sure about the fish tank. I am thinking about raising tilapia or catfish and I am gearing up to start a small system. Most of the tanks I have found seem to be quite shallow. I think I read somewhere that you want a tank that is a least three feet deep, but I have seen lots of shorter tanks and small ponds that are very shallow.
Would a rubbermaid tank that is 25 inches work for fish tank? For example: http://www.rubbermaidforless.com/rubbermaid-4247-gallon-capacity-li...

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