Backyard Aquaponics
A place to discuss aquaponics

KCl is also worth considering, especially if you need more Potassium in the system.

Todays chemistry - pH 7.4, Ammonia 0.00, Nitrites 2.0, Nitrates are still high at 160.

At what point should I be worrying about high Nitrites? Do I need to wait til this spike gets back to zero before feeding the fish again? Is the conversion rate from Nitrites to Nitrates on a 1:1 ratio? I seem to be getting heaps more Nitrates and I am not sure the plants are using them.

The brown algae seems to be slowly dissipating and I can see further into the tank almost to the bottom. The trout seem happy and even swim up to the light as its dark when I get home from work They seem to be enjoying the current from my back up pump til I get my air pump.

Still think I will upsize the return line to the tank from 20mm to 32mm to increase flow. Probably do this on the weekend.

Good news is the back up system seems to working really well and provides lots of aeration and current movement. Really pleased with the simple relay to switch it on.

Generally the conversion from nitrites to nitrates is so quick that you won't see nitrites. The salt you added should protect the fish but I'd probably withhold feed and let the nitrite reading go down. Your fish can go for a long time without being fed. The dying algae is probably contributing to the nitrite and nitrate reading. Holding back on the feed might also give you a better handle on what's going on - if your nitrates continue to go up then the algae is probably feeding the system more nutrients as it dies.

Up the aeration - It's probably just that the system is new but sometimes nitrites accumulate because of lack of oxygen.

Great - thanks Scotty. You are a wealth of knowledge, so what I am doing is on track and my thinking is correct.

How do I tell if the nitrates go up further though if I am already at the top of the scale?

First you need to dilute your current sample so that when it's diluted and you test it, it reads lower on the scale than the highest reading (right now the actual nitrates could be even higher than they read). Assuming your tap water doesn't have any nitrates then using tap water to make one of these dilutions should work (Note: SW = system water);

1 part SW + 1 part tap = 1 to 2 dilution --- multiply result by 2 to get actual nitrates in system water
1 part SW + 4 part tap = 1 to 5 dilution --- multiply result by 5 to get actual nitrates in system water
1 part SW + 9 part tap = 1 to 10 dilution --- multiply result by 10 to get actual nitrates in system water

Once you have the starting nitrates from finding a dilution that gives you a decent result you can repeat the process to see if the nitrates have gone up later on.

OK - time to fess up - Rookie mistake
Found out I had been testing my nitrates incorrectly. No wonder I was getting high readings.
I was adding the 10 drops of Bottle 1 and then shaking Bottle 2 for 30 seconds and then adding 10 drops of bottle 2. I was then shaking the tube for 1 minute. All as per the directions, except I missed one vital step.Inverting the tube a couple of times before adding drops from bottle 2

See the photo below for the incorrect and the correct results.
Tube on the left is the correct test showing 20ppm and tube on the right is the incorrect method showing horrendously high Nitrates at 160ppm

I couldn't figure out why I was always getting close to 160ppm even though I had done some partial water changes (about 4 x 150litres over a week period). Now its starts to make sense.

Typical male - doesn't read the instructions until he can't work it out.

Anyway - the trout seem happy and come up to the surface when I shine the light in (after being in the dark all day - trying to get rid of algae) Sorry guys no food until the algae clears and the Nitrites go down.

That will do it - glad you figured that out.

Re: withholding food - just till the ammonia and nitrites are gone and stay gone, you can feed while the algae is present but keep the light low and start with light feedings in case the bacteria can't handle both the dying algae and the fish waste.

Thanks Scotty. I might add some of my worms from my worm farm to the growbeds this weekend too to assist with the breakdown as well.

Bit of an update, i changed the fish tank return from 20mm to 32mm and relocated the cut off valve to more accessable position. My air pump arrived and airstone so I set that up in the fish tank too. I made a spray bar on the pump return line to the tank too. I am experimenting a bit with the number and size of holes to get the best aeration and flow.
I need to do some adjustments to my SLO height as the fish tank has been overfilling a bit. I found the SLO was not sitting right on the bottom with the bottom leg so I fixed that, but the flow has reduced so I might need to add some extra slots to increase flow a bit more.

Lots of little tweaks to make the system work better. Learning lots along the way.

Nitrites and ammonia both got to zero yesterday so the trout got a little feed. They smashed it and were coming to the surface to get the sinking pellets.
Nitrites were up again a bit today so the bacteria are still building. No feeds for them today. Nitrates (now that I've worked out the proper way to do the test) are down to 10ppm today.

I also added about 2 dozen worms to each growbed from the worm farm. They seem to be growing well too. Lots of baby worms.

Strawberries so far are not showing too many signs of the salt effect, and the Broccolini are going well. Its interesting to see that the ones I planted in the soil garden seem to be at the same stage. It will be interesting to see if this continues. The lettuce in the soil seem to be going better though.

Not much progress wth the brown algae as I brushed sides of the fish tank yesterday and muckng around with the SLO stirred thngs up a bit, but the water in the sump tank seems clearer.

Sounds like things are going better

The brown on the tank sides may turn out to be bio-slime which is normal for a system and if that's what it is I would normally just leave it alone and not clean the sides. The same thing happens to the inside of pipes so it's probably good that you changed the pipe size since this can restrict the flow through pipes.

%$#@*& Nitrites. Looks like the Nitrobacters have gone on strike or left home. I have had some high Nitrite readings for the last few days.
For the last 3 days ph has been 6.8, ammonia at between 0.00-0.25, Nitrites initially at 0.00, then 2.0ppm and then 1.00ppm (maybe 2.0ppm) and then tonight at about 5ppm Water tempsd have been consistent at 14.5-15 degrees



Fish are not being fed (and haven't for a few days when the spike first registered) and I checked the FT tonight for dead fish. I could not find any and it still looks like all 10 are there and swimming around. Its hard to do a head count when they won't stay still for more than a second so I don't think this is the issue.

I stuck the camera in there and had a good poke around and there are a couple of gum leaves and a twig or too and some fish poo in the corners but that is it. I've uploaded it here to youtube.
https://youtu.be/Z84KOY42XNg

I don't know what to make of it.

I then diluted the water sample by half with tap water and tested again and got almost the same result. It looks to me that the Nitrite reading is close to 5ppm on both tests.


I have salted to 2ppt and the fish don't seem stressed or showing any signs of distress (to me) but it worries the heck out of me. Somebody may be able tell me different from the video and let me know.

I seem to have plenty of aeration with my backup pump running 24/7 with a spray bar and the aerator as well, along with my sump pump tank.

Any ideas on what to do please? Do I just ride it out and pray and hope. Or do I do a partial water change. If I do this will it affect any more bacteria? I have emptied my rain tank and can probably only manage 150 litres of of standing tap water (pump around) in 24 hrs

5 ppm is the highest reading you can get with the nitrite test so you diluted the sample and it still gave the same result, that means you need to dilute it further to find out what the reading really is - try a 1 to 5 dilution (1 part system water with 4 parts tap). Have you tested your tap water to see if it gives a reading on it's own?

Your results make me think that either the biofilter took a hit or it wasn't far enough along in the cycling process.

Is the water you're using for water changes chlorinated or chloraminated? Doing large water changes with either in the water would probably nail your biofilter. You can usually get away with 10 to 20% water changes using chlorinated or chloraminated water but I wouldn't go any further. The fish will still be generating waste (not as much since you're not feeding them though) and there is residual organic matter that needs to breakdown in the grow beds. So whatever is coming in as waste is getting converted from ammonia to nitrite but the nitrite to nitrate step isn't doing well. Something might have killed some of the bacteria that convert nitrite to nitrate (like chlorine...) and this would explain the high nitrites. If this is the case you'll have to wait for those bacteria to re-establish themselves.

Yes I tested the tap water and zero Nitrites. I diluted to a 1:4 ratio and got the same result, reading 5ppm which means it's really 20ppm plus.

That seems extraordinarily high and I would expect dead fish at this stage. I also added some Potassium bicarbonate about 3 desertspoons in 2000 litres to try and bring the pH up a bit to try and encourage the bacteria growth. Not much I can do about the water temp to lift that to encourage growth. Fish seem not too bad at the moment, but don't know if this will last. I have 150 litres if tap water being pumped around in a separate container to try and drive the chlorine out and I can add some vitamin C to reduce the chloramines and I will reduce the water by 150 litres and then add that, but that is all I can think of at the moment. Still worrying me though. I am thinking of netting them out and putting them in the swimming pool as it has gone a bit green with the lack of attention in the cooler weather. It's probably healthier water at the moment.
Any help would be appreciated.

Just a thought but I read were you took the bell off your siphons so you didn't have to cut back on the flow from your pump adding a back pressure to it. What I used to do with my saltwater tanks is coming off the pump I would add a T with part going to the rest of the system then off the T , I would add a line with ball valve going back into the sump, this would regulate the flow going into the system, I just adjusted the amount of water coming from the Ball valve back into the sump. So if your pump was pumping too much for the bell siphons to keep up you could look into this to slow the water going into the GB while keep the pump full bore with no back preassure.

[@Kadarra - quote from other thread]
Yep I am having that difficulty right now. Panicking a bit trying to sort it out and not sure what to do. I have salted to 2ppt and as far as I can tell the fish don't seem too distressed. It's worrying me though.

May be best to have a beer and wait things out a bit.
Those numbers seem to be jumping all over the place and nothing worse than a misguided knee-jerk action.

Lots of air and the 2ppt salt will help the fish. The previous post about adding T is a good idea.
Do you have air being pumped into the fish tank ?

I am amazed that inverting the tube made that much difference particularly if you had shaken it.
The other curly one in the instructions is not to cover the cap with your finger.

If you can get some consistency in your numbers then the easiest and best option is to do water changes.
Just make sure the water you are adding is gassed off and not too different in pH.
If different pH make sure to add it gradually.

One thing that can cause nitrates to go off (and possibly nitrites) is fertiliser - particularly mineral/powder fertiliser.
Have you been adding anything like that ?