[narked]

OK Guys,

particular problem maintaining a stable PH, this has only happened over the last ten days. The reading at the moment are:

PH 7.92
KH 13
Cal 380
Mag 1120 (this is being dealt with at present) I was an idiot and didn't bother testing it.

KH is high as I just kept buffering and not trusting my test results (this has been independantly confirmed) via another test kit.

I've ruled out CO2 as the water has been heavily aeriated outside with an airpump and no rise recorded, The PH will not rise during the lighting period and continues to drop overnight.

Any ideas what could be causing this??

I recently (about 6 weeks ago) stopped using kalk as I was concerned about phosphate binding and it cost me a S&*T load of rowaphos to get it down to manageable levels close to 0.

Could the low mag be suppressing the PH to this degree?

Over the last couple of days I've carried out a 50% water change to no avail, so at the moment I haven't got a clue. At the moment nothing seems to be adversely affected luckily.


Any help would be appreciated.

[ben]

what salt do you use?
what corals have you got?
what is the ph in the morning and evening?

[narked]

ben, on Sep 19 2009, 03:05 PM, said:

what salt do you use?
what corals have you got?
what is the ph in the morning and evening?

DD H2 Ocean Salt, have been for about 12 months now.

Mainly LPS with a couple of acros, just started keeping SPS

PH this morning was 7.9, now it's 7.94. It will no doubt fall under 7.9 tonight. I'm having to use Aquavitro balance to stop the PH from dipping to far as i don't want to add any buffer due to the KH being to high now.

Should add that this is a 7 x 2 x 2 tank with 4 MP40w's driving the circulation, it's been up and running for about 2 years. There's plenty of surface movement, I wouldn't fancy taking a small boat on it.

0 ammonia
0 nitrite
> 5ppm nitrate

[ben]

im no expert on chemistry but you need to slowly lower the kh, either by water changes or by leaving the sytem to lower it naturally.

ph is sometimes best left to whatever the salt provides as stability is better than trying to buffer it all the time. 7.9 is not worth trying to raise with buffers imo.

i would also get the ph tested with another kit

[narked]

ben, on Sep 19 2009, 05:29 PM, said:

im no expert on chemistry but you need to slowly lower the kh, either by water changes or by leaving the sytem to lower it naturally.

ph is sometimes best left to whatever the salt provides as stability is better than trying to buffer it all the time. 7.9 is not worth trying to raise with buffers imo.

i would also get the ph tested with another kit

PH is monitored by an aquatronica system and has been verified by an aquamedic controller, problem is the KH is not dropping even after 2 big water changes, KH of the salt is 8, in fact all the stated parameters of the salt are what they say they should be.

[ben]

i guess the problem is the corals arnt dropping the kh fast enough, and each water change will raise it a bit more. if this is the case then you need to let the system lower them naturally which means no water changes for a couple of weeks.

i would wait for lindsay, or someone else with a better chemistry brain, to come on later and see what they say

[narked]

ben, on Sep 19 2009, 05:44 PM, said:

i guess the problem is the corals arnt dropping the kh fast enough, and each water change will raise it a bit more. if this is the case then you need to let the system lower them naturally which means no water changes for a couple of weeks.

i would wait for lindsay, or someone else with a better chemistry brain, to come on later and see what they say

will do

[lindsay]

Would let the dkh drop back on its own to around 10,at the same time very slowly buffer the mag ,keep an eye on the dkh in-case it tries to go up with the mag.The ph might be being suppressed by the rowa if its seeing allot of the tanks water and is being refilled allot.

[lindsay]

If the rowa is not the reason ,have a quick look at chasing the tail of ph by si g under reef Eden ,its a good read .

[narked]

lindsay, on Sep 19 2009, 09:21 PM, said:

If the rowa is not the reason ,have a quick look at chasing the tail of ph by si g under reef Eden ,its a good read .

Just added a dose of mag mixed with RO, put it in the sump in the chamber that the PH probe is, the bl&*dy thing dropped another 0.02 within 30 seconds. Good news is the KH is now down to 12 from 13, that's the lowest it's been for 10 days.
As for rowa, probably not the reason as this has only happened in the last week and a bit. I'm thinking that it must be the low mag. We'll see when the levels are up to where they should be.

[lindsay]

Are the calibration solutions for the probes good?.Could be that the bio-lode of the tanks fish are keeping the tank around 7.9 which is where it wants to stay now its not being bumped up by the kalk.

[Kevang]

If the probes are calibrated correctly then I wouldn't worry to much at the moment with a pH of 7.9. My old 8 footer ran at 7.9 for years without any problems. I had lots of surface movement and the sump outside but the pH still stayed at 7.9.

As Lyndsay says let the dkh come down on its own and slowly buffer the mag and see where you are then.

You may be trying to change to many parameters at once and nothing has a chance to settle down properly.

Cheers

Kev