Dosing Alkalinity Help

[Glott3133]

I need some assistance on getting my dosing accurate for my reef aquarium. I've been struggling keeping my alkalinity at 8.5. Every time I think I have it locked in, my numbers tend to drop. Even when I make minor adjustments, the all will climb to 9.0. Make another adjustment, and it will drop slowly, but continue to drop past 8.5. So I tried a test that my LFS recommended. Turn off my DOS for 24 hours, then test after the 24 hour period. Run the Seachem Dose Calculator and use that amount to set for my DOS. The problem is, my alkalinity dropped from 8.3 to 7.4. When you enter that into the calculator it wanted me to dose over 100ml per day. That's almost double what I typically dose. My Trident is almost always inaccurate, so I have been using the Hanna checker. Now I'm not confident my results are accurate with that either. I have some really nice Acros, so I really would like to get a handle on this.

Any suggestions?

 

[Tuan’s Reef]

what are you using to test alk? Is the test performed at the same time of day? What kind of corals in the tank? how big is the tank? Have pic?

 

[doubleshot00]

Is your PH dropping under 8 then goes up during the day? I noticed if my PH goes below 8.1 my alk number goes up. Now if my PH stays steady at 8.2-8.5 my alk drops fast and i have to dose more.

Also check your dosing lines and make sure its dosing accurately and it doesn't sputter. I had that issue for a few weeks.

 

[Glott3133]

My PH does drop overnight to about 8.0 then rises to almost 8.4 during the day. I've tried dosing more during the day, and less overnight, but still trying to determine what's going to keep my alk stable. What is a reasonable amount alkalinity can swing at any time?

 

[Glott3133]

I'm using a Hanna Checker and Neptune's Trident for testing. My tank is 135 gallons, with all kinds of SPS from large montipora, to small to medium acropora. Most of my acropora are still frags, but I have probably 20 of them in the tank.

 

[doubleshot00]

My PH does drop overnight to about 8.0 then rises to almost 8.4 during the day. I've tried dosing more during the day, and less overnight, but still trying to determine what's going to keep my alk stable. What is a reasonable amount alkalinity can swing at any time?

That seems normal. Check your dosing lines.

I'm no expert but it seems when i get my alk dialed (lets say stable for a month to 6 weeks) the coals just start soaking it up more. Then i have to dial it back in (takes a few days).

SPS will eat alk. After i added large acros to my tank my alk went consumption went way up.