Help ALK not dropping

renato120 · Apr 1, 2016

I use a BRS Doser, For CA and ALK. I dont know why but CA is stuck at 400 and ALK stuck at 12. I already increased the timer almost double and it doesnt pass 400.
With ALK its the same thing. I lowered the timer almost 10 min. Everyday I check with two different test kits and it reads the same. ALK @12 CA @400.
MAG is 1300.
My goal is to set ALK @10 and CA @450.

Randy Holmes-Farley · Apr 2, 2016

The calcium is easily correct with a single larger dose of calcium supplement (manual, not with the doser). This shows how much to use for many products:

http://reef.diesyst.com/chemcalc/chem_calc3.html

Then drop the drop the daily dose of both back by 25-50% and see what that does to alk over a period of a week or so.

How much alk are you dosing each day now?

jduck · Apr 2, 2016

It may be participating someplace in your tank.

renato120 · Apr 2, 2016

Randy Holmes-Farley said:
The calcium is easily correct with a single larger dose of calcium supplement (manual, not with the doser). This shows how much to use for many products:

http://reef.diesyst.com/chemcalc/chem_calc3.html

Then drop the drop the daily dose of both back by 25-50% and see what that does to alk over a period of a week or so.

How much alk are you dosing each day now?

I am dosing ALK and CA every 3 hours on a timer.
Before I was dosing ALK 17min every 3 hours. Not sure how many ml per min. ALK was around 10 for a wile. Now its at 13/14 and Im dosing 10min every 3 hours. I lowered a lot, and doesnt go down.
I just shut off the ALK doser. I want it to get to 10. Some of my sps's are bleaching the tips. I think the cause is high ALK.
Im dosing CA the same way, every 3 hours, but on a different time of ALK. As of today Im Dosing 30min of CA. I have been raising daily and no changes.

Randy Holmes-Farley · Apr 3, 2016

You need to add a large amount of calcium supplement to make a correction. Do it manually and keep the doser going to offset the ongoing demand.

Are you also doing water changes? That can mess with the values if the new water does not match the tank reasonably well.

renato120 · Apr 3, 2016

Randy Holmes-Farley said:
You need to add a large amount of calcium supplement to make a correction. Do it manually and keep the doser going to offset the ongoing demand.

Are you also doing water changes? That can mess with the values if the new water does not match the tank reasonably well.

I do weekly water changes with red sea coral pro salt.
With a salinity at 1.025 it reads a ALK of 14
Calcium at around 430

Randy Holmes-Farley · Apr 3, 2016

OK, so just make the one time correction to calcium that I that I suggested, but with that salt mix and with your target, you may need to make such a correction periodically, or up the calcium more.

It may not seem like it, but the numbers you quote for the salt mix show depleted calcium. That is because if you take that mix (14 dKH and 430 ppm calcium) and let corals use the calcium and alk in it, when you get down to 10 dKH, calcium will have dropped to about 400 ppm. So if you want 10 dKH and calcium above 400 ppm, you'll need to add somewhat more calcium than alkalinity.

renato120 · Apr 3, 2016

Randy Holmes-Farley said:
OK, so just make the one time correction to calcium that I that I suggested, but with that salt mix and with your target, you may need to make such a correction periodically, or up the calcium more.

It may not seem like it, but the numbers you quote for the salt mix show depleted calcium. That is because if you take that mix (14 dKH and 430 ppm calcium) and let corals use the calcium and alk in it, when you get down to 10 dKH, calcium will have dropped to about 400 ppm. So if you want 10 dKH and calcium above 400 ppm, you'll need to add somewhat more calcium than alkalinity.

I will make the correction. Thank you Randy

Randy Holmes-Farley · Apr 3, 2016

You're welcome.

Good luck!

psirex · Apr 5, 2016

Having a similar issue..... glad I found this thread.....

Randy Holmes-Farley · Apr 5, 2016

psirex said:
Having a similar issue..... glad I found this thread.....

Any additional assistance we can provide?

creas · Apr 5, 2016

I have question Randy, if you don't mind elaborating a little. You said "So if you want 10 dKH and calcium above 400 ppm, you'll need to add somewhat more calcium than alkalinity." I've always read that your Alk and Ca should be dosed in equal parts. Is that a hard rule or more of a rule of thumb? A year ago I had issues with precipitation, as evident by rock hard sand, but got that under control. I now control my dosers with an apex and have dialed in the numbers I like but find that I need to dose a bit more Ca than Alk. I've been trying to achieve similar parameters (dKH9.8ish, Ca 440) by dosing equal amounts but it's proven difficult. Is it okay to not be totally equal? Does Mg levels affect Alk & Ca? I seen to have an easier time keeping them constant when my Mg is up around 1400.

furam28 · Apr 5, 2016

renato120 said:
I do weekly water changes with red sea coral pro salt.
With a salinity at 1.025 it reads a ALK of 14
Calcium at around 430

My RSCP would mix at alk 11 and cal 450 at salinity of 1.026. Your alk at 14 dkh is quite high. What test kit are you using? I'd verify the test kit first, maybe by testing water at an lfs. RSCP is known for crazy variations between batches so I wouldn't be surprised if you have a batch with 14 alk.

psirex · Apr 5, 2016

Randy Holmes-Farley said:
Any additional assistance we can provide?

I think it is pretty much covered, i will triple check levels again an adjust accordingly.

Sabellafella · Apr 5, 2016

renato120 said:
I use a BRS Doser, For CA and ALK. I dont know why but CA is stuck at 400 and ALK stuck at 12. I already increased the timer almost double and it doesnt pass 400.
With ALK its the same thing. I lowered the timer almost 10 min. Everyday I check with two different test kits and it reads the same. ALK @12 CA @400.
MAG is 1300.
My goal is to set ALK @10 and CA @450.

Your issue looks like youve got your dose tuned in perfecfly, so your just raising it everytime your doing a waterchange. I was running into a higher alk situation just like this using the same salt, so i changed salt mixes and dose less alk to accommodate for the swing every wc

Randy Holmes-Farley · Apr 5, 2016

creas said:
I have question Randy, if you don't mind elaborating a little. You said "So if you want 10 dKH and calcium above 400 ppm, you'll need to add somewhat more calcium than alkalinity." I've always read that your Alk and Ca should be dosed in equal parts. Is that a hard rule or more of a rule of thumb? A year ago I had issues with precipitation, as evident by rock hard sand, but got that under control. I now control my dosers with an apex and have dialed in the numbers I like but find that I need to dose a bit more Ca than Alk. I've been trying to achieve similar parameters (dKH9.8ish, Ca 440) by dosing equal amounts but it's proven difficult. Is it okay to not be totally equal? Does Mg levels affect Alk & Ca? I seen to have an easier time keeping them constant when my Mg is up around 1400.

The statement I made was based on the salt mix being used not matching the tnak.

If the water changes did not mess with ratios, close to 1:1 would probably be best. But water changes often do, and a few minor things also can alter it (including mixing errors, inexactness of the recipe since the exact demand ratio can vary from about 18-20 ppm calcium per 2.8 dKH, and dosing pump differences in actual volume dosed)