no matter what I do.... alkalinity rises.

[John Carbonaro]

my tank is always between 11 and mid 12 dkh. i cant keep it down. when i test the newly made water, the alk is at 9.0, ph 8.3 sg 1.024. the batch of new salt water is filtered 48 hrs in the bin before being introtuced to the main tank. but... within a day alk is at 10, next day 10.5 and up and up and up.... today alk is 12.4.....corals look great, three clowns are good and two dotties are good. my baby clam is fully opened and seems happy.... the two starfish i had to put into my spare tank, as their skin started to melt in the main tank.... what is causing my alk to rise... btw, i have kept my calcium reactor off for months..... i only dose acropower. nitrate is 0 phos is.05

 

[Randy Holmes-Farley]

Do you use tap water for top off?

Aragonite sand very slowly dissolves, and if demand is very low, it can more than offset the demand.

I'm not sure exactly how acropower is formulated, but it may be adding some alkalinity.

 

[John Carbonaro]

Do you use tap water for top off?

Aragonite sand very slowly dissolves, and if demand is very low, it can more than offset the demand.

I'm not sure exactly how acropower is formulated, but it may be adding some alkalinity.

Randy, First.... I'm honored to speak with you. thank you for your interest. RO/DI (see filters in pic). one tank is ro/di water the other is salt. use ocean crystals (cheapest salt)lol

 

[arking_mark]

What is the pH of your tank?

I've noticed a direct relationship in my tank with pH and Alk. Dropping the pH tends to raise the Alkalinity.

 

[John Carbonaro]

PH 8.1

 

[arking_mark]

PH 8.1

So my understanding is:

• Your tank water started at 10dKH and has risen to 12.4dKH.
• You do regular water changes with IO Reef Crystals and measured fresh new saltwater has 8.3pH and 9dKH
• Tank pH is 8.1ish
• You only dose acro power which is supposed to be just amino acids

A couple of thoughts:

1. IO Reef Crystals usually mixes to 10-12dKH, so I'd double check your Alk tester to make sure it's accurate
2. How large of a water change are you making? If it's large enough, then I could see the Alk rising just due to the IO reef crystals mix. Not sure how long it takes to stabilize its parameters.
3. Maybe the drop in pH is raising the Alk.

 

[Randy Holmes-Farley]

1. Maybe the drop in pH is raising the Alk.

pH, alkalinity and CO2 are related mathematically. if you know 2 of them you can calculate the third exactly.

But lower pH does not directly cause alkalinity to rise. Lower pH reduces demand for alkalinity, so if you are dosing a fixed amount of alk, that may result in more dosing than is needed to offset demand, and alk may rise in that situation.