Thread: PH issues

Hi guys, I’m hoping someone can maybe shed some light on this for me, I’m having persistent issues with low ph/ph crashes (maybe the last 6 months or so)
I’ve buffered it many times upto 7-7.5 but as soon as a week later it’s rock bottom

I’ve lost 4 fish overnight, the ph is testing at 5 this evening, currently performing some water changing and buffering

Never had ph issues before and the ponds been running for many years, and at least 10 years with the current filtration setup etc ie nothing has changed recently filter wise

Bit of general info

Pond size is roughly 2500gallon raised style running an aerated retro drain into a nexus 200 then gravity return to pond, bottom is visibly clear with no build up and water clarity is great, I’m running 2 air pumps an ea 95 running the nexus and an extra 60 size running the drain air stone

Water from the tap has a ph of 7.5 so I can fix this with water changes but obviously there’s something happening in the pond itself - when it first came about it coincided with lots of rain so thought that was the cause but we’ve had no rain at all the last few times, I’m at a bit of a loss now if I’m honest!

I’ve ordered a new complete test kit as the individuals I had were old apart from the ph kit which is recent so I can update kh results etc when that arrives

Any ideas?


Sent from my iPhone using Tapatalk

I agree that the most likely scenario is low KH, however, unless you are heated I would expect bacteria activity to be very low at this time of year. In addition high acid conditions will knock back the filter bacteria.
Something else to consider is could you be getting a build up of carbon dioxide in the water? This will behave like an acid when dissolved. Make sure you have plenty of aeration and that the pond is clean. This(CO2) would be worse in winter as there is less daylight and little plant/algal activity to remove it. A build up of sludge on the bottom will decay to generate carbon dioxide and other nasties.
You've already mentioned rain (& groundwater run off) these can certainly affect ph.
Keep a very regular check on your water parameters and buffer with sodium bicarb as necessary - personally I like a KH of 5 minimum.