Backyard Aquaponics
A place to discuss aquaponics

Hi folks,
I apologize in advance for not doing a really thorough search of the zillions of posts for info about this one- I have actually tried but still can't find a definitive answer. So here goes.
My system (blog at wjastoys.blogspot.com) and http://www.backyardaquaponics.com/forum ... highlight=
is running well and we have had a fair few feeds of greens- mainly sugar snap peas, tat soi and pak choi.
However the growbeds are large( total of about 3000 litres) and the fish are very small - perhaps 100 tandanus about 50-60mm long.
I cycled with non live fish and at the start the nitrate levels were quite high- certainly over the max on my test kit ie >120ppm.
Now the nitrate is down to 5-10ppm and some of the bushes are showing signs of slight yellowing. I am using seasol but we know that there is no nitrogen to be had there.
There have been a few mentions on this forum of the hazards(?) of using Thrive or Aquasol so what do you guys do to boost the nitrogen without harming edible fish.
I guess I could just stop planting (actually stop BH) but that is no fun!

Stop Jim, don't use either or you WILL KILL your fish.

People have used seasol and maxicrop as foliar sprays which have proved harmless to fish and beneficial to plants.....

If your nitrates are low then your options are feed your fish more... get more fish..... decrease/remove the number of plants extracting the nitrates....

I'e Strawberries, tomatos and chives are all known heavy nitrate feeders.

But the yellowing might actually be more due to OTHER deficiencies lilke Iron and/or Potassium.... checlated iron seems to be the way to go for the first and Janet has been using potassium carbonate for the second (also acts as a pH buffer)... you could use soluble potash (potassium sulphate)....

Regardless, dilute mixes, applied to the growbeds not directly to the fish tank and observe repeat if necessary.....

Just take it slowly....

Hi Rupe,
Feed fish more is a possibility but I think they are eating about as much as they want- don't seem to like the sinking pellets much.
I suppose uneaten pellets are probably a small source of nitrogen but too expensive as a general concept- much better to pass through fish first.
The fish do go berserk if I chuck in live Daphnia, mossie wrigglers or chopped earthworms but that might be making a rod for my own back in maintaining the supply. For a while I thought I might have fed too much live food and like a puppie they got spoiled and didn't like the commercial stuff anymore.
More fish- must contact my potential supplier and see if he has Silver perch yet.
I agree entirely that taking it slowly is the answer.

I'd follow Rupes suggestion Jim, get some iron into your system.. My plants are growing well and I don;t get a reading for nitrates at all, they are all being used up by the plants, yet the plants are looking good.

same, EB, I never get a nitrate reading. I get all disappointed but then see my plant growth. Expect that to change as the babies turn into table fish.
Jim, u have plenty good size silvers so nutes should be there. Iron chelate is 10-15 bucks powdered from ur rural supply store for a 250-500gram tub. Teaspoon per watering can and don't spill it on ur plants, it will burn the leaves. Takes about 10 days for the new growth to show things are fine. Thereafter, once a month. You might also like to check ur pH. High or low locks out nutes.

If KG is ur silver supplier, I was there this week. They have very few left. Those that they had were on the sad looking side of things. Less than a few hundred 15cm fish. The business changed operators this weekend.
I expect they will spawn their broodfish pretty quickly,as they are ready to pop. Even so, they will not be available until the end of March.
I am not commercial, but if u are in a spot and need some fish, mine are nudging 10cm. PM me.( mods, this is not a profit making thing for me, Jim needs fish and I could prolly unload a few now I have breeders in the system)

Has anyone thought about fish emulsion (the pure stuff)?

I have mentioned this on my system thread but to keep things together I will repeat for this thread.
I have been adding 4g per day of pure(?) agricultural urea to my fish tank (4000 litres). Started about 10 days ago and have been monitoring the ammonia, nitrate and nitrite daily since then.
Bottom line- ammonia and Nitrite still Nil to trace and nitrates now about 10ppm.
And the plants are looking a lot better.
I think I will continue to add the urea daily until the fish are big enough to provide enough Nitrogen by themselves or I get a Nitrate level which is higher than seems reasonable. My system started at about 120ppm(Nitrate- both ammonia and nitrates about nil) or higher before the fish went in.

umm hehe, i've read about tilapia farmers in south east asia throwing animal manure into their tish tanks to create algea blooms for the tilapia to filter eat. I've got a goat hehe... could I through some goat pellets into my tanks to get more nitrogen into the system?

I'm pretty sure you'll get other nasties also... better if you put processed fish food in (fish shit)
Get more fish ppl, or shut off a GB

Is this right rupe have you been using potassium sulfate in your system?

AP