Low ph; high dKh

[coralgazer]

The basics:
36 gallon, 35lbs. live rock
Coralife Lunar Aqualite (2 HO T5 10,000K 31 watt lamps, 2 Actinic blue HO T5 31 watt lamps) (total of 124 watts)
DT Wavemakers: 2 Koralia 550 Evolution units
Sump: 15 gallon tank with Berlin Sock holder and 4†filter
Activated carbon bags
Bubble Magus NAC 3.5 internal skimmer
Supreme Classic Mag Drive 7 return pump
Refugium with mud bed and cheato
Water used RO (3 ppm on tds meter)
No fish or corals yet, just a small CUC
Small amt green algae and some brown looks like hair algae.
------------------------------------------

Been up and running about 4 weeks, cycled with low numbers (ammonia max: 0.5; nitrites: 1.0; never had nitrates)

Current params for several days:
T=78F
ammonia, nitrite, nitrates= all zero
SG= 1.024

Here's the problem:
ph consistently 7.9- 8.1 max (tested with ACI kit and pinpoint monitor)
Carbonate Hardness (Dkh): 15-22 dKh

When I try to raise the ph with a little baking soda, the dkh goes sky high!
How can I bring up the ph without raising the dkh?
All help appreciated.

 

[Mufasa31]

I think you should be ok with your ph.

The alk is another issue. Could be a bad test kit. I would test with another test kit. You could also test fresh mixed water and see if you get normal alk results.

 

[46gReef]

Honestly IMO your ph is fine at 7.9-8.1.....pH fluctuates for many different reasons including wether the lights are on or off, the amount of co2 in your house etc....to b honest focus on your kh, as long as thats okay then your ph is fine. I haven't checked my pH in years but monitor my kh daily, pH IMO is one of those parameters that will makwe you crazy if you let it...my .02....hth

 

[beaslbob]

1 always measure pH just before lights out.

2) to raise pH without increasing KH suck out the carbon dioxide. I would use maro algae to do that. so do what you can to exmpand the chaeto in your refugium.


my .02

 

[beaslbob]

Oh yea and stop using baking soda to raise pH. Use it to maintain kH only.

 

[Downbeach]

Your pH is fine where it is, your dKH is way over the top. You can get your pH up by opening some windows, since there's probably elevated levels of CO2 in the atmosphere.

 

[Pappy]

Baking soda and buffers raise dkh and don't do anything for ph ime. The purpose of baking soda is to raise dkh. Your ph is good but recommend doing 20% wc every 2-3 days until tests show 7-11.

 

[ColaAddict]

Dont chase your pH. Thats how alot of crash happen. If your calc, alk, magnesium within normal limits your pH should be fine. If the big 3 are normal and pH is still low then you probably have low Oxygen in your tank. Low oxygen can be fixed by better flow, skimmer, or just letting fresh air into the house

 

[ritter6788]

Solid advice given here.

 

[Chompers]

Actually...
Sodium Bicarbonate (baking soda) has a major effect on raising alkalinity and a minor effect on raising pH.
Sodium Carbonate (soda ash) has a minor effect on raising alkalinity and a major effect on raising pH.

note: major and minor are subjective and ambiguous.


Opening a window is more of a "feel good" and not really all that effective. The differences of elevated levels indoors vs. outdoors isn't usually drastic enough to effectively remedy by opening a window. If C02 is the problem, the real solution is to add a CO2 scrubber to the air inlet of your skimmer. The scrubber will remove 100% of the CO2 going into the skimmer rather than 10% of it. (A skimmer is a tanks primary source of gas exchange.)

 

[mcarroll]

Here's the problem:
ph consistently 7.9- 8.1 max (tested with ACI kit and pinpoint monitor)
Carbonate Hardness (Dkh): 15-22 dKh

When I try to raise the ph with a little baking soda, the dkh goes sky high!
How can I bring up the ph without raising the dkh?
All help appreciated.

Two things in addition to the good advice given in the thread already:

1. Low pH is a symptom, not a problem, therefore it doesn't get treated directly.
2. Baking Soda actually has a minor depressive effect on pH, so you're kinda going in the wrong direction with your chosen solution.

Were you only practicing with your pH testing gear when you noticed the trend, or did you find this while looking into a (real) problem?

Like others have said, I wouldn't presume you need to worry about your pH levels.

Maintain good mineral levels above all (recommended: 11 dKH alk, 420 ppm Ca, 1325 ppm Mg) and most likely - 99.9% of the time - everything else will take care of itself. pH monitoring can be interesting, but is not neceassary.

To this end, daily testing for alkalinity is recommended when your tank is going through changes such as during the tank's initial period and other times when you are significantly changing the coral population (aka mineral demand). But weekly or even monthly testing can suffice when things are largely stable.

Hope this helps - good luck!

-Matt

 

[dirtycontour]

Actually...
Opening a window is more of a "feel good" and not really all that effective. The differences of elevated levels indoors vs. outdoors isn't usually drastic enough to effectively remedy by opening a window. If C02 is the problem, the real solution is to add a CO2 scrubber to the air inlet of your skimmer. The scrubber will remove 100% of the CO2 going into the skimmer rather than 10% of it. (A skimmer is a tanks primary source of gas exchange.)

I'm not sure I agree with this. My pH is around 7.9 most of the year. I live in NJ so it gets really hot than really cold pretty quick. The few weeks when I can open some windows my pH stays around 8.3, IMO that's pretty drastic relatively speaking. I've never heard that the skimmer is the primary source of gas exchange. I figure the surface area of the DT would provide plenty...

 

[dirtycontour]

I agree, don't chase pH.