Need to raise dkh.

[TonyInVa]

I need to raise dkh without raising ph. My ph is at 8.29 just at the point when lights go out. dkh is at 5. So I need to raise it without raising ph. I do not have a CO2 system. Calcium is at 400ppm. What is the best way to do this?

[Coral Hind]

I use Kent Marine Super Buffer dKH

[TonyInVa]

What would cause this? This is the first time I have had low dkh but good ph.

Edited October 6, 2010 by TonyInVa

[gilmour01]

what test kit are you using to test alk?

[Coral Hind]

When did you calibrate the probe last?

What is the pH at before the lights come on?

[TonyInVa]

When did you calibrate the probe last?

What is the pH at before the lights come on?

Probe was calibrated in August. Ph before lights on is 8.07.

[Big Country]

I use SeaChem Reef Builder or Soda Ash to raise the ALK.

[F&Fmgr]

if your looking for a good way to raise the KH w/o affecting the pH you ca mix soda ash and baking soda. I usually add 3-4tbsp baking soda - 1 tbsp soda ash. the soda ash neutralizes a lot of the co2 from the baking soda. your pH will not be too affected where as using just ash(carbonate) might cause the pH to raise too much.

[Origami]

Baking soda, because of it's extra CO2 (compared to soda ash), will temporarily drive pH down. Soda ash temporarily drives it up. Both reactions, though, drive to the same point. I think you're safe to use baking soda early in the morning if you're so inclined. Just dose a mixture of it and fresh water in a manner that doesn't shift your pH by more than about 0.2 pH units over the short term.

 

For 120 gallons of water in system, you'll need about 8.5 teaspoons of baking soda to raise your alk from 5 to 8, according to this calculator.

http://reef.diesyst.com/chemcalc/chemcalc.html

Again, dose slowly.

 

However, if you've got a second test kit, check your alk again just to make sure that the reading is not off. While it could happen with a lot of photosynthesis going on during the day, that's a pretty high pH number for such low alk.

 

How often do you check your alkalinity?

[Oleg]

Probe was calibrated in August. Ph before lights on is 8.07.

 

Isn't PH at 8.07 a bit low anyway?

[Origami]

Isn't PH at 8.07 a bit low anyway?

 

He had a lights-out pH of around 8.3. I think that was his concern.

 

Tony, do you use kalkwasser? You could dose kalkwasser in the morning when your pH is lower. Raising 2.8 dkH will also raise your calcium by 20 ppm, so you'll get very close to 8 dKH and 420 ppm calcium if you use a balanced additive like kalkwasser. When dosing kalkwasser, just watch the pH spike. It's best if you drip it.

[TonyInVa]

He had a lights-out pH of around 8.3. I think that was his concern.

 

Tony, do you use kalkwasser? You could dose kalkwasser in the morning when your pH is lower. Raising 2.8 dkH will also raise your calcium by 20 ppm, so you'll get very close to 8 dKH and 420 ppm calcium if you use a balanced additive like kalkwasser. When dosing kalkwasser, just watch the pH spike. It's best if you drip it.

I am dosing Kalk.I believe the test kit I am using may be defective. Before i try anything I will get a new test kit.

[Origami]

Just remember, you lose 2.8 (or nearly 3) dKH for every 20 ppm of calcium consumed (or thereabouts). So it could be that your alk is that low if you normally run calcium closer to 420. Because alkalinity test kits are more sensitive this way, I tend to measure alk more often than calcium.

[davjbeas]

I use kent marine super DKH bufffer also. Dissolved in RODI water.

Normally my 2part dosing system is spot on but when alk runs low i use the above to raise alk.

 

David