Backyard Aquaponics
A place to discuss aquaponics

I am beginning to experience an issue with my water quality being a spike in ammonia. I have lost 3 fish in the past 4 days.

I put 150 trout in a 3000L tank back in April and have a few SP in the sump. I'm guessing we may be overstocked.

I stopped feeding them for a couple of days and rechecked the water but still the ammonia is too high.
They still want to be fed as they thrash around when I go near the tank.

I know I need to do a water exchange but I was hoping I could get some guidance on how to do it.

Do I get rid of the water first then fill or fill and empty at the same time with pump on or off?
Our bore is low in ph and they don't appear to enjoy a rapid change in acidity in one go, so have topped up in small amounts previously.

I am cycling every hour for 15 mins. Should I increase it?

Thanks in anticipation for your suggestions and advice.

More info please

What are the results of your water tests?

What is the pH of the system?

What is the pH of your bore water? And what is the pH of that bore water after you let it outgass?

How much grow bed do you have. (size of the fish tank is only part of the story.)
Do you have 6 or more BYAP 500 liter grow beds? How many are a few silver perch in the sump tank?

Thanks for your quick response.

I have 6 growbeds since April 2009 so well and truly cycled.

water temp = 13.3C

Ammonia = 2

Nitrites = 0.15
Nitrates = 5
pH around 6 (my pH meter has failed to calibrate properly this morning so was done with the water testing kit.

Water looks quite murky
( we had our first major rainfall last night for winter and found 2 dead fish this morning)

Last dead fish was found last Friday.
Our bore water is about pH of 5.5 (no idea what outgassed means however we are in designated water catchment of Perth hills and groundwater is exceptionally good quality if that helps answer the outgass query)

Thanks.

Tap water tested directly out of the pipes tends to have a lower pH than if you allow the dissolved carbon dioxide to escape (like by bubbling it for a bit) Since dissolved carbon dioxide acts as a weak acid.

Anyway, my worry at this point is that your pH has perhaps dropped too low (since it sounds like your water is not hard at all) and if you don't have any pH buffering material in your system, this could be a pH related crash. I'm kinda guessing here but since you say the drop kit says 6 and most of them don't read below 6 it could be anything lower.

These are doubly tricky to deal with since the ammonia becomes more toxic as you increase the pH but your system might not be able to process the ammonia if you don't increase the pH.

You probably should go ahead and be changing water. If you have an overflow set up, you could just let water flow in and as it reaches the over flow level, the excess can flow out. This is a more gentle way to change out water rather than dumping a bunch and leaving the fish shallow then re-filling with is more sudden. This is how I would go about doing a 20-30% water change now while also probably adding a little bit of garden lime (calcium carbonate) into all the grow beds and perhaps watering it in. I would recommend calcium carbonate in the form of powered garden lime as it will dissolve quicker being a bit more fast acting than shell grit but still slow enough acting to hopefully not spike the pH of your system up too quick. Go pretty light on the application though.
So that is for today since this is rather an emergency situation.

Then for tomorrow
If you have any barrels handy, I would suggest drawing water and adjusting the pH and let it bubble over night before using it to do the water changes tomorrow with a more controlled pH.

These are just my suggestions from a person who has never experienced low pH bore water. My water comes from a limestone aquifer and if I let it bubble over night (outgass) the pH will read between 8 and 8.4 depending on time of year and rainfall (if I check the pH right when I draw the water from the tap it will read about 7.)
Perhaps some one closer to you will have more specific suggestions for how to recover from this crash.

I wouldn't stress about water change, I would increase your pumping to 30mins or more and no feed at all for a couple of days, 150= fish is probably the higher end of the limit for 6 GB's, looks like WA is going to be wet and cold for the next few days so the cold weather will allow a higher ammonia reading, I personally think you would be better off with 100 fish in 3000lts, last year my ammonia went as high as 5 when water as 8c, but fish seemed fine so let it go for a couple of days with no food, Nitrite spiked a bit after that as well, but still did nothing and all returned to normal with no loses, your nitrite is low and will probably head up, try and add a bit more air if possible, not sure on how much you have but 150 trout will need plenty and it will also help clean things up, algae will steal you oxygen

Thanks to you both for your feedback. I'm very grateful for your help.

I will take it all on board and see what happens over the next couple of days.

L

Hi Paul and TCLynx

Just wanted to get back to you regarding your suggestions and for others to know what the outcome was for future reference to ammonia issues.

I decided to go with Paul's suggestion for both the fact that he understood local conditions and had similar extreme experiences.

After increasing the cycling from 15mins to 30mins over 2 days plus I stopped feeding, the results showed that the pH has back risen to 7.5, Ammonia dropped back to .25 and Nitrites back to 0 and no more dead fish.

Paul, can you or anyone explain the science behind this please because I don't understand why this makes such a significant difference to the water quality.

Many thanks again to you both.

Lucy

Lucy I'm not a scientist, but increasing the cycle increases filtration plus oxygen to the water, algae uses a lot of oxygen at night so can cause fish deaths, more oxygen seems to decrease algae as it uses co2 during the day (think I have the times right way around, no doubt I will be corrected ) so more oxygen = less CO2 which kills off algae, algae grows more during sunlight hours, shade cloth on or around the fish tank will also reduce algae, feeding obviously makes the fish crap which like our waste also contains ammonia, no feed = no crap so no ammonia going into the system, gives the bacteria time to catch up, thats the best I can explain it anyhow, but works for me, the Lower the pH and water Temp the more Ammonia fish can handle, this I think is because alkaline water increases the strength of ammonia, but way over my head to understand the science of that, but no doubt someone will explain.............Rupert

Increasing the pumping does increase the amount of time the bio-filter bacteria get to work on converting your ammonia and nitrite per hour and also increases aeration which does improve the bio-filter's ability to do it's job. Aeration also helps the fish and I'm glad things are back to normal.

Might be a good idea to check out the 'nitrification process'. Do a search here
'Cycling' is the action of 'nitrification', the spike from ammo to nitrite then to nitrate, then the plants in your system
take up the nitrate.