Help! Should I be worried...

[droog]

Hi,

According to my Apex controller / pH probe, my tank's PH (that has been stable at 8.1 - 8.3 for some time) started to fall this week (see attached graph).

It starts falling off Sunday 16th - this coincides with the time I swapped from T5 lighting to Radion (XR15Pro's) on my 120g tank. I setup an acclimation period of 4 weeks starting at 45% intensity ramping up to 80%.

Should I expect the pH to fall with less light (less photosynthesis) for a few weeks, and if so is this something I should pay attention to or just "let be". The skimmer is running and I have plenty of surface agitation on the water.

The graph crashed and flatlined at ph 6.9 yesterday. This had me worried initially, but then I figured it was a faulty probe. I found some Ca deposit on the probe when I got home from work yesterday so I soaked in vinegar and wiped the probe clean, rebooted apex. Vinegar and RO water were testing at the same 6.9 during this process, so I suspect a bad probe.

I started to get more normal readings again today but its still low and trending lower. Don't have any calibration fluid handy, just ordered some fluid and a cheap Chinese replacement probe.

Levels tested last night

Temp: 25.5C
Salinity: 34ppt
Alk: 7.7 dKH
Ca: 450
Mg: 1300

Alk was a little lower that usual (I try to maintain between 8-9 dKH) which would explain a slightly low reading, but not 7.2 !

Questions:

- What impact should I expect on pH when acclimating to new lights?
- If light is causing low pH what is the best way to proceed (ignore pH, ramp up the lights more quickly, or buffer the pH manually until acclimation complete?)

Does it seem likely to the experienced folk here that my pH could really be this low? I did not notice any unusual behaviour (stressed fish/corals).

I bought the "standard grade" pH probe but from what I've read they are all fairly fickle and unreliable. Is there a "better" way to monitor pH?

-droog

 

[Sk8r]

Ph doesn't matter generally, but 6.9 is a point too low. So is your alkalinity, and the fact that mg and calcium are still up says that something weird is going on. Maybe, as you say, a probe that's off. What test are you using for alkalinity, which is much more important a reading usually than ph?

 

[morleyz]

How about verifying the pH with a different test? Most liquid reagent test kits have a pH test.

 

[gone fishin]

I would suspect the probe and a lowering of your Alk. Lighting should not really have an effect. The only thing I can see from lighting is a temp decrease in the tank, from one fixture to another, but this should be negligible on pH. just my 2 cents.

 

[Wryknow]

Not sure what type of T5 set up you had before but my theory is that the newer, more intense lighting is stimulating coraline algae and coral growth which is consuming more ALK and driving down Ph. Get your Alk and CA back up to normal levels and I bet you'll be alright. You'll almost always have to adjust your dosing schedule for increased consumption rates when there's a lighting increase.

 

[Sk8r]

Cal is still a little high at 450, but I'd like to know how high it's been.

 

[Dan_P]

Hi,

According to my Apex controller / pH probe, my tank's PH (that has been stable at 8.1 - 8.3 for some time) started to fall this week (see attached graph).

It starts falling off Sunday 16th - this coincides with the time I swapped from T5 lighting to Radion (XR15Pro's) on my 120g tank. I setup an acclimation period of 4 weeks starting at 45% intensity ramping up to 80%.

Should I expect the pH to fall with less light (less photosynthesis) for a few weeks, and if so is this something I should pay attention to or just "let be". The skimmer is running and I have plenty of surface agitation on the water.

The graph crashed and flatlined at ph 6.9 yesterday. This had me worried initially, but then I figured it was a faulty probe. I found some Ca deposit on the probe when I got home from work yesterday so I soaked in vinegar and wiped the probe clean, rebooted apex. Vinegar and RO water were testing at the same 6.9 during this process, so I suspect a bad probe.

I started to get more normal readings again today but its still low and trending lower. Don't have any calibration fluid handy, just ordered some fluid and a cheap Chinese replacement probe.

Levels tested last night

Temp: 25.5C
Salinity: 34ppt
Alk: 7.7 dKH
Ca: 450
Mg: 1300

Alk was a little lower that usual (I try to maintain between 8-9 dKH) which would explain a slightly low reading, but not 7.2 !

Questions:

- What impact should I expect on pH when acclimating to new lights?
- If light is causing low pH what is the best way to proceed (ignore pH, ramp up the lights more quickly, or buffer the pH manually until acclimation complete?)

Does it seem likely to the experienced folk here that my pH could really be this low? I did not notice any unusual behaviour (stressed fish/corals).

I bought the "standard grade" pH probe but from what I've read they are all fairly fickle and unreliable. Is there a "better" way to monitor pH?

-droog

Your pH trend does not show a day-night cycle seen in most (all?) systems where photosynthesis is taking place. If your tank is empty that could explain it, otherwise, your pH reading is too stable.

When you are not regularly cleaning and calibrating your pH probe, you are running the risk of erroneous readings. This is risky with coral, less so for fish.

If the pH is really trending down, the system is increasing carbon dioxide dioxide content. That can happen if the air around the tank has an increasing carbon dioxide content, which is common in the winter. Another way to increase carbon dioxide in the system is for the exchange with the air to slow down, e.g, by covering the tank or circulation decreasing. Either one though wouldn't be so gradual.

I agree with the advice to change the probe before deciding you have an issue.

Good luck!

 

[danil]

I would keep ALK stable with good Cal&Mag level and don't worry about PH. I do have Apex but didn't check my PH probes for years. If Alk, Cal & Mag levels are fine it's most likely just probe malfunction and it has to be calibrated or replaced. Also I had some issues with Apex PH probe in the past when other device (like lights) get connected it effects PH readings. It was some sort of interference issue.

 

[droog]

Thanks everyone. I managed to find some calibration fluid last night and re-calibrated my pH probe. The new reading went straight to pH 8.01 - a little low but expected because of low Alk. So the probe did need calibration - at least it drew my attention to low Alk a little quicker than I might have otherwise.

@Sk8r - I'm using RedSea Pro test kit for Alk. I like that test kit a lot, seems accurate and easy to use.

There is a reason for the ionic imbalance. I left this out of the OP not to complicate matters, but the explanation is as follows:

I've been dosing RedSea additives (they call it Reef Foundation A/B/C but its basically Ca/Alk/Mg). The dosing regimen was dialed in but I decided to switch to Kalkwasser + 2-part because RedSea additives are not popular and very difficult to get hold of here. It was also getting expensive. I have Kalk in the ATO already, but my Alk supplement ran out before I setup the 2 part. I bought one last bottle of Alk and will hand-dose to get things in balance per Sk8r magic numbers and then dial in my 2-part dosing (TLF A, B is the only one I can find locally). I also added 4 fist sized SPS corals two weeks ago.

@Dan_P: Thanks for posting. I was worried about CO2 also but think its OK. My boilers are outside the house. There's a reasonable amount of corals in my tank but I will use your post as justification to my wife that we need more corals and photosynthesis She and the kids are catching the coral bug too so its all good!

@Danil: Agree its all about Alk. I would like to say that I ignore pH. I might have been able to ignore it this time had it not been for other things going on simultaneously. I wish there were Alk probes rather than pH ones.

-droog