Alk dropped 9.1 a 8.1 in a day

[Mick51]

My all went from 9.1 to 8.1 in a day,calcium and mag are normal wondering if excessive fans could do this I read it can by evaporation but I’ve never had this big of a drop in 1 day I used Red Sea and salifert tests And re tested

 

[WIReefer]

My all went from 9.1 to 8.1 in a day,calcium and mag are normal wondering if excessive fans could do this I read it can by evaporation but I’ve never had this big of a drop in 1 day I used Red Sea and salifert tests And re tested

Do you test at the same time everyday?

 

[Oscar47f]

Yeah as mentioned above to figure out your consumption in a day you have to test at the same time one day and the same time the next... after you do that you can figure out your alk drop by finding the difference... now if you have corals or a good amount of coralline algae this could be the culprit... if not then there may be another cause

 

[hllb]

Do you have a really heavy coral load? I would suspect one of the tests were incorrect

 

[ReefPig]

Evaporation wont cause Alk to drop, if anything it will rise, unless running fans pushes up your PH higher than normal, corals prefer higher PH (8.3+).

Have you double checked dosing, check pumps and dose rate.

1dKH should result in roughly 18-20ppm drop in calcium, but if this hasn’t dropped, then you have an Alk dosing issue.

 

[bradoo]

2,8dKH (1meq/l) =18-20mg Ca

 

[mitch91175]

My all went from 9.1 to 8.1 in a day,calcium and mag are normal wondering if excessive fans could do this I read it can by evaporation but I’ve never had this big of a drop in 1 day I used Red Sea and salifert tests And re tested

Did you do any maintenance on the system? Change GFO?

 

[Mick51]

Did you do any maintenance on the system? Change GFO?

Nothing tested around 9 yesterday it was 9.1 today 8.1

 

[Mick51]

Evaporation wont cause Alk to drop, if anything it will rise, unless running fans pushes up your PH higher than normal, corals prefer higher PH (8.3+).

Have you double checked dosing, check pumps and dose rate.

1dKH should result in roughly 18-20ppm drop in calcium, but if this hasn’t dropped, then you have an Alk dosing issue.

I just got a dosIng pump but haven’t set it up yet I’ve been doing it by hand I check all and calcium almost daily and mag weekly

 

[Mick51]

Do you test at the same time everyday?

Yes within a couple of hrs

 

[jda]

Unless you just put some Calcium Hydroxide in your tank, there is not much chance that the pH was 9.1. Probably a mis test.

 

[Mick51]

Do you have a really heavy coral load? I would suspect one of the tests were incorrect

It’s not jam packed mostly older colonies mostly acro and sps I did the Red Sea and salifert twice each and they were all pretty much the same

Unless you just put some Calcium Hydroxide in your tank, there is not much chance that the pH was 9.1. Probably a mis test.

not the PH that’s fine
Around 8.3

 

[ReefPig]

Someone else mentioned GFO above, but cannot see a response.
All GFO sucks up alk, a lot of it. When I rarely add GFO I automatically know to dose extra alk to counteract this effect.

Did you add any GFO or anything else yesterday?

 

[Randy Holmes-Farley Verified Community Expert]

My all went from 9.1 to 8.1 in a day,calcium and mag are normal wondering if excessive fans could do this I read it can by evaporation but I’ve never had this big of a drop in 1 day I used Red Sea and salifert tests And re tested

That sounds perfectly normal, and is why folks dose reef tanks: because they consume alkalinity and calcium relatively rapidly. Often 0.5 to 3 dKH per day. Sometimes more.

While you say calcium and magnesium are "stable", that too is normal but they are likely being consumed along with the alk if the alk consumption is by corals or precipitation of calcium carbonate.. The expected calcium and magnesium declines to match your 1 dKH alk decline are only about 7 ppm for Ca and less than 1 ppm for Mg, which you cannot see accurately with most kits, and is also sometimes lost in the noise caused by water changes.

 

[Mick51]

Good info thank you

 

[Mick51]

Someone else mentioned GFO above, but cannot see a response.
All GFO sucks up alk, a lot of it. When I rarely add GFO I automatically know to dose extra alk to counteract this effect.

Did you add any GFO or anything else yesterday?

Nothing