Chasing Alk?

SCReef'n · Aug 15, 2019

So I'm very new at this so I want another opinion. I have 4 lps and 1 sps frag in my 60 gallon cube. I started testing the water as I added these frags over the last few weeks and expected the parameters to be basically as advertised on the salt bucket (Red Sea Blue Bucket). Salinity is 1.026 so that should mix up to be 430 calcium 1280 mag and 8 dkh. The calcium and Mag are right in line but the alkalinity was low 7.5 dkh. No problem I thought I'll raise it up over the next day or so. Dosed 5ml of Red Sea foundation and tested the following day, 7.5 dkh again......... Ok no problem 10 ml because it apparently consuming 5ml a day. next day tested 7.5 dkh. Ok now I'm not convinced I'm doing this right. Which is more likely that my 5 frags are using 5ml alk a day or that I'm reading this thing wrong. FYI the calcium is rock steady at 420 the whole time. So tank is using alkalinity but not calcium?????? What am I doing wrong or should I just keep chasing 8dkh? Salifert test kits for everything.

Thanks for the help

EmdeReef · Aug 16, 2019

7.5 is perfectly fine I wouldn’t worry. Just pick a value and Keep alk stable.

What test kit are you using?

redfishbluefish · Aug 16, 2019

For starters, I'd use a reef calculator to see how much you need to add to raise it from 7.5 to 8.0. I used THIS calculator, and if you add 11.4 mls (assuming total volume of 60 gallons), you should see your alk go from 7.5 to 8 dKh.

Next, just to test your test methods, is to test your tank, add the alk solution, and now test again. You should see the increase in alk immediately after adding the alk solution.

Note that the addition of 11.4 mls simple raises the dKh, and does not take into account your consumption.

BeejReef · Aug 16, 2019

How old is your tank?

Since, as others have said, 7.5dkh is perfectly acceptable, I would first try to determine if you have any consumption.
Test at the same time of day for 2-3 days in a row without dosing anything and see what happens.

If it drops from 7.5 to 6.8 in two days, you can guestimate that you're consuming about .35 a day.
Just as likely, you'll see no change at all on a very new tank that may not be consuming yet.

At least you'll know if it's a matter of needing to adjust your dose to compensate for consumption, or if you need to explore other possibilities like testing error (or margin of error), salt batch consistency, dose mixing, etc. etc.

SCReef'n · Aug 16, 2019

William DeCoursey said:
How old is your tank?

Since, as others have said, 7.5dkh is perfectly acceptable, I would first try to determine if you have any consumption.
Test at the same time of day for 2-3 days in a row without dosing anything and see what happens.

If it drops from 7.5 to 6.8 in two days, you can guestimate that you're consuming about .35 a day.
Just as likely, you'll see no change at all on a very new tank that may not be consuming yet.

At least you'll know if it's a matter of needing to adjust your dose to compensate for consumption, or if you need to explore other possibilities like testing error (or margin of error), salt batch consistency, dose mixing, etc. etc.

I’ll take a few days and see what happens. Meanwhile I’m going to pick up a Hanna checker for alk and at least have a cross check. Corals seem happy and I’m not trying to chase a number for fun. It’s just I testing to me that I can’t seem to make it move. That makes me think I have a testing issue. I’ll also have my lfs double check me this weekend

W1ngz · Aug 16, 2019

Could be a test procedure issue. I had no idea interpreting syringes was sometimes problematic until I came across this thread:

Reef Chemistry Question of the Day #161 Using a Syringe

Reef Chemistry Question of the Day #160 I have just drawn tank water into a syringe with a tip (shown below, including a blowup of the barrel). The blue coloration shows where the fluid is. When I started to draw fluid in, the tip and syringe were empty and the plunger was all the way in...

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