People typically add potassium hydroxide or similar to their systems to balance pH, thus the potassium concern is normally addressed. I cannot compare the tomato and pepper crops in my system right now with soil based ones, but they do grow well, fruit and produce well if growing conditions stay within typical aquaponic range. That sales person is probably only faintly aware of aquaponics from past exposure, when it was typically considered to be a leaf crop method.
Ask the kind folk here what they think about the pepper and tomato claims :). The confusion or misinformation that comes from hydroponic type thought patterns comes from the typical nutrient levels believed to be required for growing and fruit setting. I was told a while back by one of these guys that my system will not produce because you need different mixes at different growth stages. They simply cannot wrap their head around the nutrient levels of AP and what is produced. I've got brinjal, water melon, cucumber, tomato, butternut and peppers going right now.
Lena E said:
After adding fish water 2 days ago, and 1 tsp ammonia yesterday, I still have some work to do:
ammonia - .25ppm
nitrite - .5ppm
nitrate - 5 ppm
I will add some more fish water today instead of ammonia. The water temp is 70.6 degrees. Also, I picked up some Maxicrop yesterday. The sales rep was looking for a supplemental product with more potassium because he thought aquaponics had deficiencies in potassium. He also thinks I will have a tough time growing tomatoes and pepper because they require a lot more nutrients than the fish provide. Is this true?
From your readings, after 2 days, your ammonia and nitrite are declining values, you'll probably get a zero reading within 24 hours at this rate. With ammonia at .25ppm your nitrifying bacteria are almost out of food, so to keep them alive you can dose up to ,say 2ppm(as this was your previous level), and wait for a zero nitrite reading(within 24 hours). Anytime you can dose and get zero nitrites within a 24 hour period you can consider your system fully cycled. If you allow your ammonia to go below .25ppm your bacteria colonies will start contracting and over a short time start dying.
That makes sense. He does hydroponics and his connections to AP is through Sweet Water who focuses on mainly leafy crops because it is more profitable for commercial purposes.
I'm cautiously optimistic that I will be able to succeed in AP =) I totally appreciate this forum and all of the tips and experience.
As I am thinking about adding fish, I am trying to figure out what to feed them. We would like to try to not have to rely on commercial feed, if possible. When we visited the Gardenpool (in Mesa AZ) , their fish ate about 10% duckweed, and 90% algae growing in the pool water. They had their 8 chickens pooping in the pool to help grow the algae (I think that's what it was for). The coop/cage was partially on top of the pool) and when they noticed too much ammonia, they just let their chickens more, which solved the problem. TCLynx did not recommend the chicken poop thing but I'm not sure why...maybe because of potential disease. They did not use commercial feed or black soldier fly larvae. Another amazing thing we learned was that they have never had to clean their tubes. They said the 1/2 inch tubes don't seem to get clogged. They started in 2008 and have managed to keep everything balanced.
We would like to explore the option of algae/duckweed also. I am a bit grossed out by the idea of the BSF option and could probably handle seeing green murky water instead. But s...
This should probably be included in another topic forum....
Yea, I tend to veer away from suggesting people use any warm blooded animal poo (like chicken) in their aquaponic systems since there is possibility of pathogens but people do need to make their own decisions and I don't believe in living in fear either.
If you feed your fish on algae and duckweed, there could be some competition for nutrients and I expect garden pool manages to get enough nutrients into the water with the help of the chickens (I personally would rather all warm blooded animal manure be very well composted before going into my food garden.)
Anyway, sounds like you are off to a very good start so keep thinking positive. There are definitely enough nutrients in aquaponics to grow fruiting plants, in some places light levels are actually the limiting factor.
I believe the chicken waste/algae-duckweed system is separate from the aquaponics system. It looks interesting. Tilapia needed warm water year round.
Lena E said:
T We would like to try to not have to rely on commercial feed, if possible. When we visited the Gardenpool (in Mesa AZ) , their fish ate about 10% duckweed, and 90% algae growing in the pool water.
Thanks for your encouragement, TC. I am not ruling out BSF because it does seem like a good way to compost all of the kitchen scraps....I have to get over the gross factor. You use BLF, right? Do you use commercial fish feed too?
Light will be our biggest challenge up here in WI. Even with a greenhouse we will have a lot of cloudy/short days for many, many months of the year.
We grow some BSF but not too many get fed to the fish, the chickens and ducks tend to get first dibs on those since they beg. (And since we have chickens, we seem to have far less stuff to put into the worm and BSF bins too.)
I do use commercial fish feed for my catfish. I'm always keeping my eyes open for alternatives but I'm also not about to turn growing fish feed into a full time occupation to feed my fish since I'm unwilling to pay that much for my fish feed.
Someone said this once on my blog...can you wonderful science types verify if this makes sense or not...
So you should use ammonium bicarbonate (NH4HCO3) (to start a cycle and keep the bacteria alive) which has a stable PH (Buffer effect ) of 6.36 instead of pure ammonia NH4OH which has a PH of 9 more or less and it does not act as a buffer.
and if true, where would you even get ammonium bicarbonate?
I'd have to check Sylvia... but I can't see how a "bicarbonate" could have a stable pH value of 6.3
Carbonates, and doubly strong BiCarbonates form the basis for pH buffer to raise pH...
Sounds like an oxymoron to me...