chronic low ph

[nvert]

Hi Randy-
I think that I have a very weird ph situ here.

Is it possible to have low ph when all other parameters are are above par? For the past mont, my ph has consistently hovered between 7.7 and 8.0 while on the other hand alk and ca averages are 12dkh and 450. Ammon, nitrites/trates are 0. I drip about 1.5gal of kalk nightly (no reactor) and use IO for my w/c change (1x mo, 1.026) - all RODI filtered. What bothers me even more is that my ph is highest right before the ligths come on and the kalk stops dripping while, instead, the ph slowly DROPS during the day! I test using Salifert and have replaced batteries and the probe for a new one in my Pinpoint. I'm also callibrating with Pinpoint. I run an airtube that's attached outsided the house to my tank's sump since C02 buildup was happening in my closed home. This tank is sps/clams dominated with very little problem algae. It is a 6 month old 120g upgrade from my 40g full reef that was 2.5yrs old.

I have not found anything online pertinent to my situation and am hoping that you might have some answers. Thanks for your help.

Brad

[Randy Holmes-Farley]

Is it possible to have low ph when all other parameters are are above par?

Absolutely. That is very common. Excess ambient CO2 levels in your tank and/or home will drive down the pH. When you stop the limewater, the CO2 keeps coming in from the air, and sends pH back down, regardless of the time of day.

Have you tried the aeration experiments described in this article?

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

[nvert]

Hi Randy-
Yes, I did try the experiment and therefore ran an air line outside to bring in fresh air...probably this bit of info got lost in my lengthy narration above!!! Any other ideas?

Brad

[Randy Holmes-Farley]

s, I did try the experiment and therefore ran an air line outside to bring in fresh air...probably this bit of info got lost in my lengthy narration above!!!

Must have been a different thread. It's hard for me to keep track of all 3,219 pH threads :D

Can you raise the amount of limewater? Maybe increase evaporation with fans? Maybe try milky limewater?

[Bojan]

Originally posted by nvert
HiYes, I did try the experiment and therefore ran an air line outside to bring in fresh air...probably this bit of info got lost in my lengthy narration above!!!

What is the result of your aeration experiment.

I suggest you to fill one glass with tank water and put this glass in room , where aquarium is located. After few hours Ph measured with your Ph probe have to be 8,5 (based on KH=12, normal CO2 level).

If PH is lower
- your PH probe is not calibrated correctly
- or you have excess ambient CO2 level
- or both

If PH is lover Aerate glass with outside air and Ph have to be 8,5

If not
- your PH probe is not calibrated correctly
- or your city has excess CO2 level
- or both

[NCNBilly]

You don't live in Pittsburgh by any chance? =)

[nvert]

Hi Guys-
I did all of that....aerated a 1/2gallon of tank water for an hour outside and it went from 7.8 to 8.2. I'm trying to increase evap so I can add more kalk to see if that helps.

BUT...why would the ph be going down when the lights are on? In three years of reefkeeping I have never witnessed this.

[manderx]

can you slow down the dripping so it can go 24/7?

[Randy Holmes-Farley]

BUT...why would the ph be going down when the lights are on? In three years of reefkeeping I have never witnessed this.

Because you pushed it up with limewater at night, and then without it, the unusually high ambient CO2 levels drove it back down.

[Conky]

Matt and Brad,

I drip 24/7 (about 15 gallons a day) and haven't seen any real problems with it (though there is probably always excess CO2 in the reactor effluent). Usually keeps it around 8.1 at night and 8.2 around noon. Without it my swings are similar to yours, Brad.

[nvert]

Randy-
Over the last three years, I've always pushed my ph up at night with kalk drip just as most reefers do in order to compensate for ph drop when the lights go out. Prior to all this trouble my ph was 8.2 before the lights came on (after nightly kalk drip) and 8.4 when they went off. The nightly kalk dosing kept the ph from dropping below 8.2 and the lights raised the ph to 8.4.

But I'm still wondering why my ph drops during the day when my halides are on...Everything I read says that ph goes up when the lights are on.

I added another fan to increase evap rate so I can add more kalk but my numbers still are low.

B

[Randy Holmes-Farley]

You may be confusing two different phenomena.

The pH changes day to night due to consumption of CO2 by photosynthesis during the day. So by that effect the pH rises during the day.

But the ambient CO2 in your home air can easily drive the pH down if it is higher than the equilibrium pH for that amount of CO2 in the air. The limewater raises it up, but when you stop the limewater, the ambient CO2 whacks it back down.

Try taking a cup of tank water in the early morning when pH is high, and in the evening when it is lower,and aerate both with an airstone inside for a hour. See what effect that aeration has on the pH of each.

[nvert]

Not to beat a dead horse but I'm pumping fresh air from outside my house into my tank. Maybe it's possible that this is not enough fresh air??? I'll take your test though and let you know what happens. Thanks man.

[Randy Holmes-Farley]

Yes, that is certainly possible. The fresh air via tubing to a skimmer does not always work. The entire top of the tank is still exposed to high CO2 house air, and it gets in that way.

[nvert]

....that's what i was thinking. the second fan indeed increased my evap rate so i was able to drip more kalk last night. ph was up to 8.4 this morning. I imagine now that the drip is off the ph will steadily drop but hopefully not past 8.0. I can accept these parameters if so....

thanks.

[Randy Holmes-Farley]

That sounds like a good result so far. Spreading the drip out over a longer period may also help. :)