Stumped w/ PH problem

[scottgjerdingen]

I have a 125g tank that I have had up and running for ~ 6 months now and I now have a PH problem that I cannot seem to overcome. My PH climbs to 8.3 by the end of the day (if dosed w/ Kalkwasser in the morning, w/o Kalk it only climbs to 8.2) and over night it drops to 8.0 (and below this if not dosed w/ Kalk in the morning). I am a bit concerned that the alkalinity level is too high to keep adding buffers to keep the PH up so I have been using Kalkwasser every morning to keep the PH up and I am concerned that this is not a good thing either.

Current readings are as follows and are measured @ 7:00 pm (2 hrs before lights off):

Temp 78-80 (morning/evening)
Calcium 450 - steady
Alk 16+ dKh - steady
Mg. 1350 - steady
SG - .24
Nitrite/Am - 0
Nitrate ~ 10
Redox 330 - steady
Lighting – 600w PC
Water flow is ~1500g per hr (into the sump + ~ 300 per hr in the tank)
Filtration – skimmer/fiber pad
~ 200 lbs live rock
~ 2-3 inch aragonite substrate w/ 10 lbs Garf Grunge
All H2O added to the tank is RO/DI

Stock
~ 20 various corals (stars, Goni, acrophoria, monte, frog, etc.)
~ 10 fish (tangs, gobys, wrasses)
Lots of crabs, snails and 2 starfish

Other factors that I though may contribute are:
1) O2 - I am circulating ~ 1500g hr and it gets quite good airation in the sump but the sump is in a cabined enclosed on 3 sides (back is open) and the tank has a glass top w/ vented hood
2) Dirty filters – cleaned/replaced weekly
3) H2O changes - 10-15% weekly

Stock in the tank seems to be doing well with the exception of 2 xenia’s that have toppled over (1 still remains in good shape).

I have done a fair amount of research on this and I still do not understand the extremely high dKh and the PH remaining lower that I want it w/o dosing Kalk. What I am experiencing is contrary to almost all that I have read, either that or I just don’t get it? Any words of wisdom would be greatly appreciated.

tia

- scott -

 

[Anonymous]

It is perfectly normal for the PH in the tank to drop overnight. It happens because plants (algae and zooxanthellae) have different chemical interactions when they aren't photosynthesizing. Furthermore, a daytime PH of 8.2 is almost perfectly where you want it to be, and anywhere between 8.0 and 8.4 is where you want the range to stay. It doesn't seem like you have anything wrong at all.

 

[scottgjerdingen]

Thanks SC. I do understand the reason for the drop over night, the problem I feel I have is that I am maintaining PH by dripping ~ 1 gal of Kalkwasser daily and I did not think this was a good thing...may be it is and it is time to research a reactor? Otherwise, if I don't do this my PH will slip out of the range I am operating at now (e.g. 7.8 in the morning, 8.1 in the evening).

I am also a bit leary that I may set off a "snow storm" dosing this much calcium (I am also adding 35cc of B-Ionic daily) with my alkalinity > 16dKh. Are there ways of increasing PH without increasing alk or ca levels?

tia

- scott -

 

[liquid]

You may want to take a look at this article from April's issue of Advanced Aquarist:

INDOOR AIR QUALITY
by ROBERT JORDAN
The Effects of Carbon Dioxide On pH
http://www.advancedaquarist.com/issues/ ... /short.htm

Along with the following articles:

Alkalinity
by DBW
http://www.ozreef.org/reference/alkalinity.html

CHEMISTRY AND THE AQUARIUM
by RANDY HOLMES-FARLEY
The Relationship Between Alkalinity and pH
http://www.advancedaquarist.com/issues/may2002/chem.htm

FWIW, your alkalinity seems a bit higher than I would run it. I'd run it more around 10-12 dKH if it were me. Other than that, your pH swing is perfectly normal and if the tank were mine I wouldn't even be worrying about it.

Shane

 

[scottgjerdingen]

Shane - I had seen the Advanced Aquarist article yesterday and it prompted me lower the water level in my sump to get more churning going on in the sump (previously the water level had been fairly high minimizing the potential of O2 incorporation?)...it'll be interesting to see if that helps address the problem. If not I'll probably need to rig up a way to get more air movement into the sump area.

I am not too concerned about this being an issue but I'd like to think we are on to something here! :idea:

-scott -

 

[liquid]

Really, the bottom line here is: are your corals and other animals and critters in your tank looking fine or stressed due to this low pH "issue"? If not, then I'd leave well enough alone myself.

Shane

 

[Marcosreef]

If not I'll probably need to rig up a way to get more air movement into the sump area. -scott -

The room you keep your tank is also important to note. If the room has poor air circulation, CO2 can build up and eventually creep into the water.

I was having problems with a chronically low pH, and after keeping a window slightly open in my finished basement during the day, has helped greatly with this.

Regards, Marco

 

[danmhippo]

Hmmm, Interesting.....

If the room CO2 concentration relative to appropriate normal air CO2 concentration is so high, that without intentional injection to dissolve in water is able to bring down PH, I wonder what reaction human would have if stayed in that room for prolonged period of time?

 

[Marcosreef]

Hmmm, Interesting..... I wonder what reaction human would have if stayed in that room for prolonged period of time?

I wonder this too, Dan. I have yet to install the HVAC in the room, the only means of fresh air would be an open window.

I spend considerable time in here with my wife, so the CO2 concentration must get pretty high.

I will do more research on this. This is somthing that could affect Kalkwasser usage as well, if excess CO2 in the air could speed-up formation of insoluable calcium carbonate in the container.

Regards, Marco

 

[danmhippo]

Scott, do you have lots of macro algae in the sump and your lighting is 12/12?

The reason I am asking is that I have 2 refugium and normally I run 24/7 lighting in the sump. Last week, my PC bulb broke in half and I have to shut down for a night to get them replaced the next day. I noticed my ph swinged from 8.2 to 8.0 overnight. My tank is heavily stocked and sand bed is deep, which both of these factors in combination with dark period for macro algae can lead to ph swing.

I don't know if this applies in your case.

 

[scottgjerdingen]

Dan - my sump is relatively free of algae, it is only 6 months old and is not illuminated so I expect a dip of sorts (shooting for something like 8.4 down to 8.2 over night).

Earlier CO2 conversations are leading me to believe I have followed some potentially bad advise in the past. About 6 weeks ago I got my own RO/DI unit and I have been storing H2O in 55 gallon tubs and have been circulating it with a Rio 2500.....I was told with this level of circulation I would not need to introduce additional 02.

For grins I measured the ph on my holding tank tonight and it was 7.6 (salt mix, SG @ .24). Unfortunately I have not measured this in the past but this seems to be a bit low and I am wondering if it may be due to 02 depletion and this is causing my low PH problem...same thing with my "make-up" water reservoir (ph 6.9) that I use for making both salt solution and mixing kalk?

If this seems logical I guess I need to acqire an o2 test ket to confirm and then if confirmed deal with it. If this may be the case what are the solutions to addressing this?

- aerate the tank more than normal and aerate my holding tanks?
- dump my holding tanks and get fresh/aerated h2o and do massive h2o changes?

tia

- scott -

 

[danmhippo]

A misconception: high CO2 concentration in the air does not equal to low O2. O2 and CO2 are different gases, and concentration of either can be low or high or both low or both high.

 

[scottgjerdingen]

Good point!

 

[beerbaron]

HOUSEPLANTS WILL FIX BOTH AND THEIR ALMOST AS COOL AS AQUARIUMS