Riddle me this...Alk problem

[KJoFan]

Long story short, my Red Sea Alk test was not reading the proper color at the end point, so I ordered a brand new one.

I tested Alk on Saturday and it tested at 6.4 dKh. I adjusted my DOS to meter out enough ESV solution to increase Alk by 0.5 dKh over a 24 hour period.

I re-tested on Sunday and Alk tested 7.4 dKh. I thought perhaps I'd mis-calculated my dosing pump but decided against adjustments and to re-test today.

I tested tonight (previous two tests were done mid-late morning) and got 6.4 dKh again. So, I re-tested and again got 6.4.

Is this to say my tank is legitimately using 1.0 dKh in a day?

This is a Biocube 29 with lps, zoas and about 14 sps frags all looking fine, encrusting, etc.

I want Alk to be around 7.0, current level is too low. But, do I increase dosing to dose equivalent of 1.0 dKh in a 24 hr period?

 

[Randy Holmes-Farley Verified Community Expert]

1 dKH per day is certainly normal. Low end of normal. Coralline algae alone can soak up more than that.

So it is fine to dose that amount daily for a while and see what happens going forward.

 

[KJoFan]

1 dKH per day is certainly normal. Low end of normal. Coralline algae alone can soak up more than that.

So it is fine to dose that amount daily for a while and see what happens going forward.

Thanks Randy. I had found previously this level of dosing or even less had been sufficient to keep alk up. But the addition of sps, even though frags, are encrusting and growing so must be using more than I anticipated.

I will up the dosing by another 0.5 dKh and test and see where that puts it.

I figured a lower, drifting lower alk was better than a spike. But, seems I'm trending up which is good. Shows growth of something at least.

 

[Randy Holmes-Farley Verified Community Expert]

Sounds good.

Happy reefing.

 

[KJoFan]

I increased the dosing two days ago to equate to a 0.5 dKh increase (not accounting for usage) based on current tested level of alk. So, if it was at 6.4 three days ago, I was aiming for 7.0. I tested the day after increase and it still tested at 6.4 so I increased by another 0.5 dKh and tested yesterday. it was at 7.0 dKh so I left it alone.

Today I tested again (all tests done at relatively the same time of day) and it was at 7.8 dKh.

Is it possible to dial it in such that it will actually stay stable? I've backed off dosing by an equivalent of 0.25 dKh.

I don't understand what is happening.

Also, I have not been running the Ca doser for several days and it continues to test at 475-480. Why am I experiencing hardly any drop in Ca?

 

[Randy Holmes-Farley Verified Community Expert]

Calcium changes far more slowly than alkalinity when consumed or overdosed. A change of 1 dKH corresponds to only a change of only about 7 ppm calcium, which will usually go undetected.

The demand for both changes (rises) as the alk and pH change (rise), so dialing it in can take a while. Also, don't overreact to daily changes as much of it may be just testing error.

 

[KJoFan]

Calcium changes far more slowly than alkalinity when consumed or overdosed. A change of 1 dKH corresponds to only a change of only about 7 ppm calcium, which will usually go undetected.

The demand for both changes (rises) as the alk and pH change (rise), so dialing it in can take a while. Also, don't overreact to daily changes as much of it may be just testing error.

I don't track pH so it could play a factor I'm sure. I've never really felt the need to track it before, and maybe I don't need to now either.

I am trying not to react to any one test, as I'm sure there is some margin of error. My main concern is finding a place for dosing that will be adequate for a week or so. I will be leaving for Christmas 24th through the 30th, so am a little worried about leaving things less than dialed in. I don't have a tank sitter nor the option to have one. But, as yet, I haven't had any dangerously low or high readings, it just hasn't been rock solid.

 

[jenreefer]

The time of day that you test also will affect your numbers. I always retest when a number seems off, and try to make sure that I am not testing right when the tank is being dosed as this can give you a high reading also. Test morning noon and night until you leave to confirm you are on the right track.

 

[Mpierce]

In regards to ph and alk consumption check out this BRS video:

 

[KJoFan]

The time of day that you test also will affect your numbers. I always retest when a number seems off, and try to make sure that I am not testing right when the tank is being dosed as this can give you a high reading also. Test morning noon and night until you leave to confirm you are on the right track.

I have been testing at the same time of day each day. Alk is dosed in even increments throughout the day, so testing once per day at the same time should be somewhat accurate, in my mind.

I can't test multiple times per day as I am at work all day, hence testing in the evening when I get home.

 

[jenreefer]

I prefer to dose Alk at night to compensate for the nighttime drop in Ph. If you are testing at the end of the alk dosing, you may be getting the high point. You may be getting a big drop at night. Test before you go to work to make sure to see what the low point is. JMHO

 

[KJoFan]

I prefer to dose Alk at night to compensate for the nighttime drop in Ph. If you are testing at the end of the alk dosing, you may be getting the high point. You may be getting a big drop at night. Test before you go to work to make sure to see what the low point is. JMHO

I thought of that too. I had been dosing only overnight, but when I increased the amount I spread it out to the entire day. Maybe I should go back to only dosing in the overnight and see if that gives me more steady readings.

You could be right, that I'm just catching it at a time when it's peaking.

 

[reefwiser]

Testing three times a day is the best is it let's you see the actual consumption of alk over the whole photo period. Do it on a day your off and see your readings. I dose 7 times during a 24 hour period to maintain a contain level.