Backyard Aquaponics
A place to discuss aquaponics

While your biofiltration is establishing, water changes are your only real option (or consumption by duckweed etc - but I'd not rely on this at the stage you are, ie HSM). For that reason you want to restrict to the greatest degree possible the production of ammonia, ie keep the feed right down.

To make your ammonia less toxic, you could reduce your pH some, though make sure that you do this gradually if employing this option, and don't reduce it to a level where the cycling of your system (ie establishment of biofilter) suffers. I wouldn't go lower than 7 at this stage.

Do another water change adn monitor ammonia, pH and temp. What is the max temp you are getting to?

+1

max temp today was 17 deg, we've stopped feeding the fish. Were feeding them about 3/4 teaspoon a day of ground up fish food. We will change the water tomorrow. The fish size are around 30mm to 60mm. Should have bought a test kit sooner!

Is that water temp or air temp Kelly?

water temp

Consistent with what we suspected... exxcept the pH is way different from the 6.2 you posted from the other test kit...

You said "Temperature going from 12 to 16 throughout the day".... was that air or water temp Kelly??



Salt will help.... if you had to "siphon out the marron poo" then I think you may have had an oxygen problem (and obviously an ammonia problem as well) from decomposition...

Had heard something about azolla before... if true that's lowered your DO further...

At 17 degrees and a pH of 7.8.... your ammonia tolerance (TAN) is only about 0.6.... you're reading 2.... fatal to fish....

If you're still reading that level of ammonia after the 33% water change... then it must have been off the scale before...

Retest, and if the ammonia is anywhere near 1 or above....then I'd do another 33% water change I think... to get it down further...

Here's the ammonia/pH chart for reference...

When we bought the fish from the fish farm he was shocked to hear we had galv tanks and said all the metals eg. lead in solder, iron, can eventually kill the fish. Are our fish in trouble again soon?

Hey Rupe - have you caught Steve's reading disease. Read from the last page mate

The older style gal tanks were often soldered with a lead/tin??? solder....

There's been discussion as to possible affects from the zinc as well....

The newer tanks are lined with aquaplate and are OK...

Nah VB.... just trying to flick back and forth between here and an assignment... you guys are just to quick for me tonite....

Anyway... what you on about big boy...



Read the chart... scan down the 15 degree line... not the 10 degree line ....

I wasn't using that chart Rupe - was using a more precise one, as published in the BYAP Magazine

Now I'm going to have to go look.... like I haven't got enough going on...

Wow... big differences between the charts... now I'm going to have to look up the "real" one that they use at Natfish...

Ok from my Natfish notes...

Un-ionesed ammonia (NH3) = [ (TANx%value from table) x 1.2 ] / 100

.. 2 x 1.84 x 1.2 / 100 = 0.044... or 4ppm...

5 ppm is fatal...

From the "Nessler" ammonia tables... result is 0.036.... 3.6 ppm.... boderline, start of fatalities according to their charts...

Disregard...


Should read...

Ok from my Natfish notes...

Un-ionesed ammonia (NH3) = [ (TANx%value from table) x 1.2 ] / 100

.. 2 x 1.84 x 1.2 / 100 = 0.044... or 0.04ppm...

0.05 ppm is fatal...

From the "Nessler" ammonia tables... result is 0.036.... 0.036ppm.... borderline, start of fatalities according to their charts...

About the metals. Yes the zinc in the galvanization on the tank can be bad for fish, especially at the lower (more acidic) pH. Also, zinc in the water can make copper more toxic. However, the marron or other shell fish are likely to be more affected by such things. Most people successfully using galvanized tanks, have lined them or they are coated in some way or another.