low PH-??

fchaulk · #1 10-21-2005, 12:37 AM

Problem with my PH being low

I have a 70gal tank with 65lbs of live rock and a 3" crushed coral bed. The tank has been running for 4 months. I use RO/DI water for water changes and the PH always drops everytime the water is changed. Been trying to change the water slowly to try and get the KH down a little. At least I think this is the right thing to do.

SG=1.024
PH=7.8
Calicum=400mg/l
KH = 280 mg/l , high
Ammonia , Nitrate & nitrite all are excellent

Any suggestions would be appreciated.

Thanks
Frank

reeferaddict · #2 10-21-2005, 01:19 AM

Frank,

I think you are possibly misinterpreting your test results. I think 280 mg/L should be translated to 2.8 mq/L (millequivalents) or around 7 - 8 dKH (Degrees Karbonat Hardness - a European term, but one I happen to find easiest to measure) This is fine, albeit at the low end of the normallt acceptable range. Maybe try and get your reading up to 10 dKH and see how that affects your pH. Other than that, the only other thing I can think of would be causing this would be too much C02 in the system or a decaying animal... but then you would get an ammonia and nitrite spike.

Have a look at Bev's water chemistry links in the Reef section for more reading on this...

fchaulk · #3 10-21-2005, 01:54 AM

Thanks , I am probably misinterpreting the dKH for sure but I just checked the test kit I have and it did work out to 280mg/l . The test kit says the ideal range is between 105 to 125mg/l . I have the nutrafin KH/GH test kit. I will go and have a look at the link you are suggesting I need to understand the water chemistry better for sure.
Thanks
Frank

Doormatt · #4 10-21-2005, 04:20 AM

Are you aerating your RO makeup water for 8+ hours (and heating it) before introducing it to the tank?

Beverly · #5 10-21-2005, 10:44 AM

Another thing to consider is if your tank room is getting enough fresh air. Too much CO2 and not enough oxygen in the tank room will also depress pH.

fchaulk · #6 10-21-2005, 12:15 PM

I read some last night and I turned on the Air exchanger and this morning the PH was up by .1 , maybe too much C02 in the room as Beverly suggested.

I do heat my RO water but I do not aerate it. I do check the PH before though and it always around 8.2 . I will try aerating it as well for my next water change.

Still have to do some more reading from Bev's water chemistry links as well. Did some last night , but a lot to understand in one go.

Thanks
Frank

Beverly · #7 10-21-2005, 03:02 PM

Frank,

Make sure you aerate the water in a room with lots of fresh air, otherwise you will be mixing more CO2 into your new saltwater.

Great to hear pH went up after turning on your air exchanger. I'll bet if you keep it on from now on, your pH will eventually stablize at a much higher level.

As for the reading, do it in several shots, and reread material over time. It took me several months of reading to get even the most basic understanding of what's going on chemically in my tanks. Of course, I'm a chemistry dummy, and old