3.9 - 4.0 PH ? WTF

[flamenco-t]

I am having trouble keeping my PH up.

90 gallon with heavy load
W/D Filtration
Emperor 400

I can bring PH up using baking soda, but it always fall back down to 3.9 -4.0 range. I also added epsom salt to raise up my GH value.

I did 30% water change with 7.0 water and it stays at 4.5 ish and I wake up in the morning to find it falls back down to 3.8-3.9

My fish are doing fine. I use Pinpoint PH digital monitor (calbirated) and veriy because it read 8.1 on my reef tank (verify with salifert test kit).

I opened all doors and window and run air bubbles to drives CO2 out and it will raise up to 4.5-4.9, but it falls back down at night to 3.9

In summary, I can bring PH up with Baking soda and Magnesium, but having trouble keeping it up.

Any suggestion ?

stan

 

[WyldFya]

Your problem isn't co2. While co2 does affect pH, it wouldn't do that much, unless you are injecting with pressurized co2. The problem is likely the stock load. What fish do you have, how big are they, and how much and what do you feed? Do you do gravel washes/gravel vacs? I'd be willing to bet the filters have a lot of build up on them, and your substrate has a lot of detritus trapped in it.

 

[cartersvillealex]

Your problem isn't co2. While co2 does affect pH, it wouldn't do that much, unless you are injecting with pressurized co2. The problem is likely the stock load. What fish do you have, how big are they, and how much and what do you feed? Do you do gravel washes/gravel vacs? I'd be willing to bet the filters have a lot of build up on them, and your substrate has a lot of detritus trapped in it.

I had the same problem in an overloaded 120 and couldnt figure it out for months. Turns out it was exactly this. powerheads were not pulling enough volume from the UG filter, and detritus was building up under and causing the pH to drop. Vacuum that gravel and do 50% water changes a few times and it will come back up.

 

[flamenco-t]

Sounds good...thank you for the input.

Everyone is going into a 240 gallon so I will be okay.

I know my tank is overstock, I haven't clean the filters and media in preparation for the move trying to keep as much as bacteria as possible.

But this will all change this weekend.

stan

 

[csx4236]

Need some alkalinity/ph buffer

 

[DiXoN]

have you tested the hardness of the water, i had a similar problem with my ph dropping over a 2 week period and it was due to no buffering capacity.
i added a couple of bags of crushed sea shells, i bought a kilo and seperated them into 2 bags and added one to each filter taking one out later as it was not needed.
my ph stays around 7.2 now.