What causes a sudden daily variance in alk consumption?

[Sierra_Bravo]

I use two part with a doser and generally check alk every day to every other day using a Hanna checker. I'll see small daily variances of 1-2 tenths, generally in one direction only, and as I see the trend I'll tweak the timers on the dosers a second or two to make a correction. I expect that is normal for those of us that do not use CO2 reactors. I'll see a very small change sometimes when I perform a water change as well.

However, sometimes I'll have a sudden change (within 24 hours) of more than .5 - usually down - as if the tank suddenly increased alk consumption. Nothing in the tank has been changed. My pH will typically show lower as well.

I'm just curious if corals have growth spurts, if it's more of a testing issue, or something else? Does the pH level change play a role?

 

[DipSpit]

Following along. I have seen this too, though not recently. I always chalked it up to test error based on some tank variable.

 

[jolt]

I've seen this too, and I test twice a day with consistent results, so for me I don't believe it's a testing issue. Always assumed it was a bunch of happy corals at the same time

 

[Michael A Kurolvech]

I would agree, I think I've managed to attain consistency in my parameters and attribute the occasional dip to a growth spurt. I've seen it both in calcium and alkalinity.

 

[justin.k.nelson]

I have seen this as well and I test daily. I always assumed that my sudden spike was due to coral increase and manually dose back to my set 7.5 smh. I f I see a trend over 3+ days, I'll adjust my alk doser. These swings is what I think hurt me in the end when I had a calcium reactor hooked up.

 

[PatW]

I have seen this also. I had it happen just this morning. I test ALK daily. If the move is a bit bigger than normal, I do a follow up test just to be sure. This morning both results were exactly the same. Do all the corals in the tank go “one, two, three!” ?

 

[Sierra_Bravo]

I have seen this as well and I test daily. I always assumed that my sudden spike was due to coral increase and manually dose back to my set 7.5 smh. I f I see a trend over 3+ days, I'll adjust my alk doser. These swings is what I think hurt me in the end when I had a calcium reactor hooked up.

As simple as that is, I had not thought about doing a manual dose to get it back to norm and continue to observe. If it continues to drop than adjust the dosers for the extra consistent demand. If it stays normal, than it was just a blip of increased consumption for "whatever" reason and no harm done. If it is suddenly higher the next day than it was probably a testing error.

I was upping the doser and then having to spend several days adjusting and readjusting to get it back to the level I wanted.

 

[Randy Holmes-Farley Verified Community Expert]

There are many things that could alter alk demand daily, in addition to test error.

A big one that folks cannot so readily control is pH, which may vary a lot depending on open/closed windows, wind, number of people in the home, outside temperatures, etc.

 

[Greenstreet.1]

In the morning after alk Pump stops I’m at 8.6 in the night before pump start I’m at 8.3 I don’t worry about it as all is happy and I thank that drop as what the tank use during the day as I don’t dose alk during the day.