Backyard Aquaponics
A place to discuss aquaponics

Kelly, +1 to buying a test kit.

I think your pH is so low for the fish that it seems to them that their skin is burning - maybe that's why they're so stressy. Did you try anything to get the pH a little higher?

I have no idea what the effect of high chlorine values is, but I thought that it would dissipate quickly with all the circulation and aeration in aquaponics.


My pH is very low as well (6-ish), and I did suffer from two strange fish deaths some weeks ago too. My fish don't exactly seem healthy, but at least no more fish deaths for now.


Mine are, now and again. Parasites? Salt alone doesn't help against parasites, by the way.

One more thought. If you are feeding the fish- how much? and as the system is quite new it is more likely that too much food or uneaten food can be increasing the ammonia in your system. If the ammonia is not being converted it will build up in the system causing it to become toxic to the fish. More fish have been killed by adding too much food in the early days. Kinda like killing them with kindness. Don't know of fish being killed cause they didn't get fed. I have known of fish that have lived for more than six weeks without the addition of food.
I know it is the hardest thing when the system is new and you have just got fish to not feed them. Especially when every time you have visitors it can become time to feed the fish, and of course they are always sooo hungry. Withold food. IMHO

On the contrary Xzorby... salt has been found to be highly effective against parasites... especially ICH....

Being able to manipulate the water temp, in conjunction with salt, can shorten, interrupt and ultimately stop the life cycle.

The point Steve makes about Chlorine is important...



Bottom line.... Chlorine in the water will kill off your beneficial bacteria... lessening your fitration capacity....

Chloramine in the water, with the right pH, will add to your ammonia load....

If you've been over-feeding your fish, as Faye suggested...

Then you'll have added even more ammonia to the tank, and lessened DO, as uneaten feed decomposes...

Couple the extra ammonia load, with degarded filtration capacity due to the chlorine knocking out the bacteria....

Lower DO and a pH of 6.2.... all up, at the very least a major stressor for the fish...

Even if not immediately fatal... and the fish behaviour points to them "burning"... then their elevated respiration, movement and metabolism... all of which leads to greater oxygen demand...

Will leave your fish immune systems at a point where secondary infections like fungal attack will occur...

You definitely need a test kit pronto Kelly... an immediate 50% water change... and IMHO 3ppt of salt (after the water change).....

Salting will in itself promote production of a slime/mucous coat... which ease the "burn" and lower the stress on the fish... as well as providing a physical barrier to infection.

Then you need to buffer your pH back to a better level... the water change will help.... with Calcium Carbonate (quick)... and/or shellgrit for a longer term (slower/ongoing) buffer....

Just make sure you test the water change water for chlorine... off gas it by leaving out in sunlight, preferrably with an airstone for at least a day...

If you have chloramine, as opposed to chlorine, in your water supply, then it will not offgas in a day.

That's true VB... in which case you may have to add some water conditioner...

Check with your local water authority Kelly.

I always use neutraliser. It's really quite impractical (and too risky)IMHO to do it any other way, unless of course you are collecting your own water.

Hi Kelly, may have had something similar,
see viewtopic.php?p=130660&sid=b287b2aadac666176ed66e4564d4b520#p130660
and follow few posts down

had no problem since then, except for two fatalities last week on one nite
and another lost SP this week, no apparent reason but the water temp. was going down
to 6'C for two or three days in a row on both occasions.

My SP are between 70 and 90 mm only.

First of all thanks heaps for all the info. Just got in from work did a test of the water ( yes I did get hold of a decent test kit ) the results : nitrite 0.25, nitrate 0, ph 7.8 ammonia 2. The tank has been filled with rain water, it is an old rain water tank ( galv ). Put in 3 ppt salt today prior to testing (about 5 hrs ).Changed out about a 3rd of the water while siphoning out the marron poo yesterday. Had a visit today from an aquaculture guy with s/p in farm ponds. He spotted something that we over looked. Azola ? (don't know the spelling ) that a friend had given me saying that it was duck weed.He said that this takes oxygen out of the water and thinks that the roots are toxic to fish ( a friend of his lost all their sp's when this was in their dam ). Can anyone confirm this? Needless to say have removed and destoyed the plant, heard that it is an illegal plant........ Have lost another dozen fish today. Need time away from work just to look after them.

At that pH, your ammonia level is toxic to the fish. The amount of total ammonia that is in the unionised form (which is the toxic form) increases with pH and temp. As an example, at pH 7.8 and temp 16 degrees, the safe level of total ammonia (which is what your test kit would have measured) is 1.1 parts per million (your is 2ppm). At higher temps it is even less.

First of all thanks heaps for all the info. Tested the water tonight after work ( yes i did get a decent test kit )results ammonia 2 nitite 0.25 nitrate 0 ph 7.8. The tank is an old rain water tank ( galv ) filled with rain water. Had a visit today from a guy with sp's in farm dams on a big scale. He noticed something that we had over looked AZOLA. A friend had given this to us saying that it was duckweed.He said that he thought that this was toxic to s/p. Can anyone confirm this ? Needless to say we have removed and destroyed plants (told that it was illegal to have too ).Salted the tank 3ppt at about 3 pm today did the water tests at about 8 pm. Water was changed out by about a 3rd yesterday when we siphoned out marron poo etc. then replaced with stored rain water........ Have had about a dozen fatalities in the last 24 hrs. Hope we're getting close to fixing the problem. Need to stay home from work so can look after them.

A negative on the Azola roots being poisonous to fish to my knowledge. Many people have azola in their ponds/tanks.

THanks V B interesting. How do you decrease the ammonia

water change

best way is to convert it...
Azola that I know of is not noxous to fish.
but it does suck O2