Question about KH.

Robink · Jan 29, 2018

Approximately 6 months ago I switched from manual dosing of calcium and alk to BRS dosers.
When I was dosing manually I was adding upwards of 100 mls daily of both. My kh was testing between 8 and 9. Since adding the doser I have had to continually decrease the dose and the kh was stable for months adding approx 75 mls of each daily. Recently, last month or so, my kh has been climbing, so I've been decreasing the dose every few days, and I'm now down to dosing 61.2 mls daily. Is this normal?
I have approximately 70 corals, mostly sps, in the tank. Some are frags and some small colonies.
Only had a few not doing well. Most corals growing well, good color.
Tank: 108 gallon DT
Calc: 460
KH: 9.3 (today)
Mag:1460
N03: 5
P03: 0-.02
SG:1.026

Randy Holmes-Farley · Jan 29, 2018

I don't know if normal is the word, but the demand depends strongly on the alk level, so if the alk level was rising after a once a day manual dose, you may have consumed more during that period right after dosing than you would later in the day after the alk and pH dropped back to pre-dosing levels.

Robink · Jan 29, 2018

Ok, so now I'm using a doser and it's dropping. I have the dosers set up to dose calc and alk on the hour, alternating between the two, so each is dosed every two hours over a 24 hour period. Is it the way I'm dosing?

Randy Holmes-Farley · Jan 29, 2018

Robink said:
Ok, so now I'm using a doser and it's dropping. I have the dosers set up to dose calc and alk on the hour, alternating between the two, so each is dosed every two hours over a 24 hour period. Is it the way I'm dosing?

That's a fine way to dose. I would not worry about the reduced demand unless corals look to not be thriving.

rkpetersen · Jan 29, 2018

I had a very similar experience. I just couldn't keep up with demand with manual dosing, and the alk/pH swings were taking a toll. When I switched to a doser, both alk and calcium levels quickly climbed despite dosing the same exact total amount as I had manually, such that I had to eventually cut back on both calc and alk by about 20%. This discrepancy was probably due to increased abiotic precipitation of calcium carbonate that occurred with manual dosing (despite following the usual instructions about separating the doses physically and temporally), and which did not occur with the much more frequent smaller doses provided by the doser.

Robink · Jan 29, 2018

Randy Holmes-Farley said:
That's a fine way to dose. I would not worry about the reduced demand unless corals look to not be thriving.

Thank you.

Robink · Jan 29, 2018

rkpetersen said:
I had a very similar experience. I just couldn't keep up with demand with manual dosing, and the alk/pH swings were taking a toll. When I switched to a doser, both alk and calcium levels quickly climbed despite dosing the same exact total amount as I had manually, such that I had to eventually cut back on both calc and alk by about 20%. This discrepancy was probably due to increased abiotic precipitation of calcium that occurred with manual dosing (despite following the usual instructions about separating the doses physically and temporally), and which did not occur with the much more frequent smaller doses provided by the doser.

At this point I've cut back more than 30%.

Randy Holmes-Farley · Jan 29, 2018

Robink said:
Thank you.

You're welcome.

Happy Reefing.

Robink · Feb 25, 2018

Well I kept lowering the dosage and alk kept creeping up. Finally figured out my apex was turning on my dosers, have no idea why. I know this is usually operator error. Apex has been working fine for about a year now. Don't know why it would all of a sudden do this. Manually dosed for a day and changed the program on the apex. Seems to be working now but I will be checking it constantly. ;Bored