Backyard Aquaponics
A place to discuss aquaponics

Yep, you'll definitely need some higher protein pellets for the Silvers... and a higher feed/waste rate... should help kick your nitrification along a bit...

Okay Rup think i'll purchase some pellets through your website do you post to melbourne? And what sort of delivery cost would be involved.

1/2 dozen stubbies would help Amonia

PM F&F... he knows where you can get feed down your way... save the freight cost...

Froggo - Seasol has no Nitrate at all. It is a nutrient tonic only.

I second that OBO, seasol is a trace nutrient and potassium supplement, doesn't really add nitrates (unless you are using one with fish emulsion added which isn't recommended for aquaponics as it can overload the bio-filter.)

As to tap water and pH. If you are reading your tap water pH right out of the tap, it could be a false reading. It might be higher that you think. Read here to understand why.
http://backyardaquaponics.com/forum/viewtopic.php?f=11&t=3894

Looking at the leaves of the zucchini, I would say it is suffering a nitrogen deficiency. Get the system cycled up and things should be better there but this will take time. Hopefully the new feed will help.

If you are really impatient, a small amount of pee in the ponics is a cheap quick way to up the nitrogen but I don't really recommend that in a system with fish. You are probably better off being patient. As the system gets cycled, the pH will likely come down. Your pH is probably high from the tap water but just make sure you don't have any thing like concrete or limestone tucked into the fish tank as hides or something. Those will buffer pH up.

I have a few handfuls of 20 mm screenings in the bottom of the tank which i thought would be a good idea, harbour some muck and help to cycle. Is it advisable to have rock in the bottom of FT. I have read mixed opinions about this in another thread.

No.

When you want to catch the fish, that muck gets stirred up and kills them instead. Instantly.

ooh! that could be bad.

thanks for the head up on that....

Matt

Yep, can't see any benefit in having gravel in the bottom of a tank....if you can remove it asap... even if you have to do so in small lots... letting the tank settle in between...

Hi everyone,

sorry guys I was being a bit lazy calling seasol a nitrate as such. Seasol has a fair bit of potassium which we all know comes in quantity from seaweed/seawater.

Potassium as I understand is a form of nitrogen. In seasol it's in the form of ionic salt, potassium nitrate readily precipitates from salts. This is why the seasol label says virtually no nitrogen.

In our AP system this is converte via decomposing organic matter into potassium nitrate(nitrogen).

In effect it speeds up the cycling process by converting urea, food scraps and organic plant particles, algae into nitrates.

God bless froggo.

Hi Froggo,

Nope.
Both Potasium (K) and Nitrogen (N) are naturally occuring "Elements". The atmosphere is made up off about 78% Nitrogen gas!! (N2). Potasium is a metal and highly reactive solid while Nitrogen is an inert non-metal gas, which is why they can bond to form "Compounds" in the presence of Oxygen etc. Such as Potasium Nitrate (KNO3) known as Saltpetre, which is a naturally occuring Mineral source of Nitrogen and used for explosive mixtures as well as a preservative. That's why fertilisers are used for explosive mixtures, it's the cobinations formed with Nitrogen which makes them so powerfull. Nitro-Glycerine is the prime example.(C3H5N3O9). Dad used to mix diesel with Ammonium Sulphate ((NH4)2SO4) which contains 21% Nitrogen, to blow stumps out of the ground! Ammonium Nitrate ((NH4)(NO3)) is more powerful to mix with Fuel Oil and it is commonly called "Anfo".
Hope this helps to explain a bit of Chemistry.

Cheers IanK

This is a good link to explain Nitrogen activity as it applies to basic chemistry.
http://www.dynamicscience.com.au/tester ... /urine.htm

Cheers IanK

Thank you Ian for explaining it so well. I don't have that good a chemistry background myself.

Anyway the normal big three elements needed in fertilizers N-P-K Nitrogen-Phosphorus-Potassium three different things. Nitrogen we get abundantly from fish wastes and we normally measure this. Phosphorus is also abundant in fish wastes though we don't normally measure it for the aquaponics. Potassium is not so abundant in fish wastes which is why many of us find some supplementation needed. Seasol has the potassium as well as many other trace nutrients and is a good general tonic for the plants.

As to the gravel in the fish tank, it does not benefit the fish and can cause you issues in the future. It is advisable to remove it from the tank. (Only exception to that rule would be for display aquariums but people keeping such aquariums already know about cleaning them regularly and not having too many fish or feeding them much, totally different from normal aquaponics.) Only other exception might be in a yabbie tank.

Hi Ian,

yes it's another one of my sweeping generalisations instead of giving a big chemistry lesson which
can tend to bore people stupid.

Potassium(K) is what you say but when it's added to our AP water you get the famous reaction
we want which produced potassium nitrate(KNO3),saltpetre, nitrate of potash, nitre.

Nitrogen(N) would be the gas given off from this reaction?

God bless, froggo.