Backyard Aquaponics
A place to discuss aquaponics

Hello! Just recently started doing the Aquaponics. Been really enjoying it. Have about 850L setup. 9 blue tilapia, 3 plecos.

Finished my fishless cycle not long ago. I've read all over the place but have been having a hard time with Nitrite levels for Tilapia. I LOVE data. . . so I've included a screenshot of my system as it is. I am thinking the recent Ammonia and Nitrite spike might be the snails that I didn't manage to get out of the tank that died, and the new "natural fish fertilizer".

Any vets that stop by, I would love a little advise. Take a look at my chart! As far as tests I use an IR therm gun and the API master kit.

Hi Nils, welcome to the forum and AP. Data is good for making decisions. It's good you are watching your water, this is very important for new systems. It is typical to see a nitrite spike after adding fish, though you have few fish so I am a little surprised.

Do you have salt in your system? Chloride ions will prevent the Nitrite from binding with the fish's blood and prevent brown blood disease (nitrite poisoning). Typically 1ppt salt is more than enough, but it must be chloride salt like NaCl or KCl. So for your system adding 850 grams of salt would do it. Be sure to use "clean" salt, not table salt. Pool salt, aquarium salt, or water softener salt (solar salt) are good sources. You don't want any iodine, anti-caking, de-scale or rust inhibiting additives. Just salt.

Otherwise do 30% water exchanges to control your nitrite.

I just added salt today as per scotty's advise. I found pure salt as pickling salt at the store. everything else had additives. I added it to my sump tank so it can dissolve over time and go to the fishes.

My nitrite is settling back down. I think maybe I was overfeeding the fish, and in combination the plecos dying caused the bump.

keep in mind that there are two bacteria involved - one does ammonia-nitrite and other does nitrite-nitrate.
.
so most likely an indication that the system had not fully cycled at that time and/or population of Nitrite-Nitrate bacteria was not substantive. The data appears to show the ammonia-nitrite phase developing in late April thus the peak. Once the second stage nitrite-nitrate bacteria are present in sufficient numbers then your nitrites dropped off - which hopefully should remain case now if you keep things steady. Nice set of data.

with a cycled and balanced system you should see nitrites staying down.

>> the new "natural fish fertilizer".

yep that would do it. Check the box/container and you probably find it has quite a bit of nitrogen.
you probably going to need a seaweed extract liquid fertiliser that is low/lower in Nitrogen.


system might still move a little bit as it is new. Best bet initially once fish added is to keep feeding relatively low.
if you see any ammonia or nitrite build up just stop/reduce feeding for a few days.
Be careful using fertilisers etc that have nitrogen or urea. These also add a ammonia/nitrite load to the system.

things have smoothed out a bit. thank for the advise! Still waiting on that pH to lower. I thought using RO water as top-off would help but it hasn't made a dent yet. The fish probably aren't happy. . . not that I can see them with the eddha iron. But I still see them move towards the surface when I feed them.

>> Still waiting on that pH to lower.

it may not - it is not something to look for or expect from the cyling process.
It is usually a longer term outcome, but may never happen in some systems.
definitely not to be expected as a definite result in a new system.
If there is buffering available in the system (or top up water) pH can stay up - it is not unusual.

RO water won't bring the pH down specifically - although it is often low pH it offers nothing to react with (it is mostly low pH due to gaseous acidity). Basically it will just water the system down. If you just had RO water the system would be highly unstable and jump all over the place (killing quite a few fish).

what is the equipment/device you are using to measure nitrates, nitrites, pH and ammonia?

Pretty sweet. I ran out of strips and think I need something more reliable.

The RO water I have added has a pH of 7. I am assuming with dilution it would eventually lower the pH.

Question: Do buffering agents get absorbed by the plants or leave the system in any way, or will I need to do water swaps, something I am not too keen on. I take out about two gallons of water a week to clear the swirl filter, and add about 10 gallons of the RO water. I think once the system is more established it will require more water per week.

As far ask testing equipment, I just use the API test drops. Of it goes over, I very carefully cut the water to test with clean water and test again. I don't assume my graphs are 100%, but judging by the curves I must've done alright.

>> Do buffering agents get absorbed by the plants or leave the system in any way

it depends on what they are and what the plants need.
eg. if you artificially buffer for low pH with KHCO3 (potassium bicarbonate) then the K will most likely get used.
demand for Ca varies (often Ca if it is scheme buffered water or lime/limestone based).
or else something else (eg. if hard water from ground sources)
If you really want to know test and monitor your KH and GH.

Yes RO will dilute but dilution does not change the pH necessarily.
RO water has no / very low reactive capacity (Acid - Base) as it basically has nothing in it.

But why worry about your pH at this early stage of your system ? [ if it is not media related ]
IMO the biggest take-home message around this forum is that people who muck around with their systems too much inevitably end up having ongoing issues.
If you get pH down too soon you risk that you will end up treating for acidity anyway.

If it really concerns you then use HCL (hydrochloric/muriatic acid) as recommended variously around this forum.
(via your top up water and/or removed water not directly into system)


>> I don't assume my graphs are 100%, but judging by the curves I must've done alright.

they are fine. The only real option you have for pH is a decent properly calibrated meter.
API is OK provided you are aware of its limitations and valid ranges of its tests.
Typically the best info-for-cost option.

>> not that I can see them with the eddha iron

why are you using iron at this stage ? And why at levels that you cant see the fish ?
refer to these threads > viewtopic.php?f=14&t=26641 and viewtopic.php?f=12&t=26890 (Mr Damages comments)
you only use iron if your plants tell you they need iron (and same for everything else)
if you cant see your fish you are using way too much.

This has been my general mantra about the system in general. Taking steps slowly. Not sweating. My main concern right now is getting more plants in the system so the roots can expand the biofiltration, and to keep the fish alive. I am mainly concerned about the pH because of the TAN graph.



Yes, I would agree. Thing is, I really didn't think 1 tsp was going to color 250 gallons that much. I was basing it on a youtube video from bright agrotech(?). Once I added one tsp and it changed that much I immediately stopped. Plants seem to be doing better though with that ammount. Thank you for the links! It strengthens my belief next time I can add even less. Probably 1/4 tsp. It's started to clear up a bit with the small water trades I do. Honestly though, I think the fish have preferred the murky water. They seem less stressed to me, and I think it's cut down on algae too. I only added the iron because my plants were looking very sick and a foliar iron spray seemed to help alot, after a very small change from a cal/mag spray. If you look in my system thread I was getting advice over there.


As far as KH/GH last week they were at 7 drops before the top-off.

It is always like that for people starting out. Most of us here are/were all in same boat - it is really trial and error for each person as the systems are all different in some way and ultimately their needs are unique. I have 5 fish tanks with same water source and you still get notable differences between them.

Agreed on the fish - it is funny how we strive for crystal clear water yet the fish are naturally happy in murky water.
I tend to keep some pots and pond plants in my tanks as a personal preference and I always have enough nitrates etc.

The iron one is a classic - there is a high correlation between posts about red stained water and replies from Mr Damage but too much iron is not a good thing either.start to wonder at recomendations on some sites and then there is the human factor - packet says x so twice as much must be twice as good.

You dont need to worry about the TAN with your numbers. It is mainly if the ammonia start creeping up and/or there is insufficient oxygen.most fish that like warm water are bit more resilient anyway.

HCL will get your pH down and reduce the buffering it is best option but I would hold off going much bekow 7.6 in a new system.