Can't raise ALK

rdnyva · 07/10/2008, 04:57 AM

I have been battllng a low ALK/low PH problem. ALK is consistently 2.86 meql. I add 250 ml of 2 part every morning. Calcium is at 500 (a bit high) and Mag is steady at 1300. My PH is 7.8 in the morning, rises to 8.2 after dosing, down to 8.0 at lights out and 7.8 in the morning. The ALK calculator told me that 1232 ml would be needed to raise my ALK to 4.0, but I thought that would be too much to add all at once so I just doubled my dose yesterday to 500 ml of ALK and did not add the Cal part. The PH went to 8.4 but has dropped back to 7.8 as of his monring. I tested my ALK and it is back to 2.86 this morning. So my double dose yesterday did nothing to raise the ALK. What would be your recommendations.

FWIW my corals and fish look great although I've noticed growth is very slow.

Randy Holmes-Farley · 07/10/2008, 05:04 AM

FWIW, 2.86 meq/L is not low. It is just fine. I recommend 2.5-4 meq/L, and the ocean is a tad under 2.5 meq/L.

What two part are you using?

Would you describe the tank as having a lot of coralline and/or hard corals?

The pH is dropping due to excess CO2 in the tank water. More aeration with fresh air, or maybe using limewater will help. This article has more:

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

rdnyva · 07/10/2008, 05:17 AM

Thanks Randy, I realize 2.86 is not low, but I thought it was on the low side and wanted to raise it. I was using your recipe #1 for a long time (2 years) but recently tried Oceans Blend with the same results. The tank does have a lot of coraline and I am moving towards sps in addition to a crocea clam. I don't think the PH problem is a result of excess CO2. My sump is located outside and the skimmer constantly pumps in fresh air. Thanks again for your help.

Randy Holmes-Farley · 07/10/2008, 05:53 AM

FWIW, with normal alkalinity, low pH MUST be due to excess CO2 in the water. Maybe try the aeration test I describe in the article. It could also be your pH measurement is off.

If you do not see excessive precipitation of calcium carbonate in your sump or elsewhere, I'd just add more of the alk part each day and see how the alkalinity goes (assuming you want to raise it).

rdnyva · 07/10/2008, 01:13 PM

Thanks for the advice. How would handle adding more ALK, would you just increase the amount of ALK each day and keep the Cal part the same or increase both parts equally.

Randy Holmes-Farley · 07/10/2008, 01:14 PM

With calcium at 500 ppm, I'd add just the alkalinity part until calcium drop to 450 ppm or so. Then resume equal parts dosing.

rdnyva · 07/12/2008, 05:43 AM

Randy, first I want to thank you for all your great advice. But I think I'm mising something here. My ALK tested at 2.86, and twice this week I doubled my dose of ALK part (250 to 500) and skipped the Cal part. I tested this morning and although my Cal dropped from 500 to 430 the ALK remains at 2.86, shouldn't the ALK have risen even a little. I don't get it. What is your take on this?

BTW - I'm using Salifert test kits.

Billybeau1 · 07/12/2008, 05:58 AM

What brand supplement are you using ?

You have a lot of water volume. You may want to try raising your alk level up with baking soda first, then resume the 2-part.

Check the calculator for amounts to be added. You'll see bs is much cheaper.

Randy Holmes-Farley · 07/12/2008, 06:03 AM

It is possible you have an off kit, but there is also substantial negative feedback against raising alkalinity: the higher it is, the more you need to keep it there. Corals, other organisms, and abiotic precipitation all increase their consumption as alkalinity rises. So as you add more, the equilibrium value you reach is not as high as might be expected.

The effect is not usually as extreme as you are seeing, but I would not worry excessively about adding more unless you begin to see substantial deposition of calcium carbonate near where you are adding it.

07/10/2008, 05:04 AM	#2
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 81,937	FWIW, 2.86 meq/L is not low. It is just fine. I recommend 2.5-4 meq/L, and the ocean is a tad under 2.5 meq/L. What two part are you using? Would you describe the tank as having a lot of coralline and/or hard corals? The pH is dropping due to excess CO2 in the tank water. More aeration with fresh air, or maybe using limewater will help. This article has more: Low pH: Causes and Cures http://reefkeeping.com/issues/2004-09/rhf/index.htm __________________ Randy Holmes-Farley Club 65535 Current Tank Info: 120 mixed reef

07/10/2008, 05:53 AM	#4
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 81,937	FWIW, with normal alkalinity, low pH MUST be due to excess CO2 in the water. Maybe try the aeration test I describe in the article. It could also be your pH measurement is off. If you do not see excessive precipitation of calcium carbonate in your sump or elsewhere, I'd just add more of the alk part each day and see how the alkalinity goes (assuming you want to raise it). __________________ Randy Holmes-Farley Club 65535 Current Tank Info: 120 mixed reef

07/10/2008, 01:14 PM	#6
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 81,937	With calcium at 500 ppm, I'd add just the alkalinity part until calcium drop to 450 ppm or so. Then resume equal parts dosing. __________________ Randy Holmes-Farley Club 65535 Current Tank Info: 120 mixed reef

07/12/2008, 06:03 AM	#9
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 81,937	It is possible you have an off kit, but there is also substantial negative feedback against raising alkalinity: the higher it is, the more you need to keep it there. Corals, other organisms, and abiotic precipitation all increase their consumption as alkalinity rises. So as you add more, the equilibrium value you reach is not as high as might be expected. The effect is not usually as extreme as you are seeing, but I would not worry excessively about adding more unless you begin to see substantial deposition of calcium carbonate near where you are adding it. __________________ Randy Holmes-Farley Club 65535 Current Tank Info: 120 mixed reef

07/10/2008, 04:57 AM	#1
rdnyva Registered Member Join Date: Oct 2002 Location: Ocala, Florida Posts: 802	Can't raise ALK I have been battllng a low ALK/low PH problem. ALK is consistently 2.86 meql. I add 250 ml of 2 part every morning. Calcium is at 500 (a bit high) and Mag is steady at 1300. My PH is 7.8 in the morning, rises to 8.2 after dosing, down to 8.0 at lights out and 7.8 in the morning. The ALK calculator told me that 1232 ml would be needed to raise my ALK to 4.0, but I thought that would be too much to add all at once so I just doubled my dose yesterday to 500 ml of ALK and did not add the Cal part. The PH went to 8.4 but has dropped back to 7.8 as of his monring. I tested my ALK and it is back to 2.86 this morning. So my double dose yesterday did nothing to raise the ALK. What would be your recommendations. FWIW my corals and fish look great although I've noticed growth is very slow.

07/10/2008, 05:17 AM	#3
rdnyva Registered Member Join Date: Oct 2002 Location: Ocala, Florida Posts: 802	Thanks Randy, I realize 2.86 is not low, but I thought it was on the low side and wanted to raise it. I was using your recipe #1 for a long time (2 years) but recently tried Oceans Blend with the same results. The tank does have a lot of coraline and I am moving towards sps in addition to a crocea clam. I don't think the PH problem is a result of excess CO2. My sump is located outside and the skimmer constantly pumps in fresh air. Thanks again for your help.

07/10/2008, 01:13 PM	#5
rdnyva Registered Member Join Date: Oct 2002 Location: Ocala, Florida Posts: 802	Thanks for the advice. How would handle adding more ALK, would you just increase the amount of ALK each day and keep the Cal part the same or increase both parts equally.

07/12/2008, 05:43 AM	#7
rdnyva Registered Member Join Date: Oct 2002 Location: Ocala, Florida Posts: 802	Randy, first I want to thank you for all your great advice. But I think I'm mising something here. My ALK tested at 2.86, and twice this week I doubled my dose of ALK part (250 to 500) and skipped the Cal part. I tested this morning and although my Cal dropped from 500 to 430 the ALK remains at 2.86, shouldn't the ALK have risen even a little. I don't get it. What is your take on this? BTW - I'm using Salifert test kits.

07/12/2008, 05:58 AM	#8
Billybeau1 Registered Member Join Date: Jul 2005 Location: Dyer, Indiana Posts: 12,164	What brand supplement are you using ? You have a lot of water volume. You may want to try raising your alk level up with baking soda first, then resume the 2-part. Check the calculator for amounts to be added. You'll see bs is much cheaper.