Very uneven calc/alk dosing

[TheEngineer]

Before you say testing error, I've redone the test 4 times with a Hannah checker for both.

I consistently need 2mL of BRS 2 part alk daily to maintain in the high 8's DKH. My calcium slid, issue with my doser so I've been doing it manually, down to 380. I dosed 50 mL of calc which should have gotten me to ~410. I tested the next morning and it was at 390. I dosed another 50mL, tested the next morning and I was at 395. I dosed another 50mL, tested the next morning at I'm at 400.

That seems way off to me. Am I missing something?

 

[Brew12]

Before you say testing error, I've redone the test 4 times with a Hannah checker for both.

I consistently need 2mL of BRS 2 part alk daily to maintain in the high 8's DKH. My calcium slid, issue with my doser so I've been doing it manually, down to 380. I dosed 50 mL of calc which should have gotten me to ~410. I tested the next morning and it was at 390. I dosed another 50mL, tested the next morning and I was at 395. I dosed another 50mL, tested the next morning at I'm at 400.

That seems way off to me. Am I missing something?

What is your estimated water volume?

 

[Randy Holmes-Farley Verified Community Expert]

Before you say testing error, I've redone the test 4 times with a Hannah checker for both.

I consistently need 2mL of BRS 2 part alk daily to maintain in the high 8's DKH. My calcium slid, issue with my doser so I've been doing it manually, down to 380. I dosed 50 mL of calc which should have gotten me to ~410. I tested the next morning and it was at 390. I dosed another 50mL, tested the next morning and I was at 395. I dosed another 50mL, tested the next morning at I'm at 400.

That seems way off to me. Am I missing something?

It seems like a correction to boost, right? Not a long term dosing imbalance while trying to maintain both?

What salt mix are you using? What size tank are we talking about?

A salt mix like normal IO has a substantial imbalance of high alk and low calcium, so you need an unbalanced dosing scheme to maintain calcium and alk with a mix like it.

 

[Brew12]

If I remember correctly, you have around 50g total water volume. To go from 380ppm to 410ppm I'm showing you would need around 150ml.

 

[Randy Holmes-Farley Verified Community Expert]

If I remember correctly, you have around 50g total water volume. To go from 380ppm to 410ppm I'm showing you would need around 150ml.

2 mL of BRS alk additive in 50 gallons of tank water is an almost insignificant 0.06 dKH per day.

At that incredibly low level, one will not expect equal parts dosing because a variety of tiny effects can add 0.06 dKH of "apparent" demand.

That said, nothing uses up calcium in large amounts that is not using alk.

 

[TheEngineer]

Yes, this is a correction to boost at this point.

Yep, 50g cube. I always calculate based on that as the total volume. I use Red Sea Pro, but I haven't done a water change in a few weeks.

When I did the calculation last, it said I needed 120 mL to get to 420 or something like that. I always dose half to make sure I'm moving it the right direction and won't overshoot. Not to mention that's a lot to dose at once.

My concern is that 50mL should be moving me up by 10ppm, but I'm really only getting about 5ppm. So let's say that means I'm consuming 5ppm per day, that would mean I need to dose 25mL per day to maintain right? That's 12.5x what i dose alk at.

 

[Brew12]

2 mL of BRS alk additive in 50 gallons of tank water is an almost insignificant 0.06 dKH per day.

At that incredibly low level, one will not expect equal parts dosing because a variety of tiny effects can add 0.06 dKH of "apparent" demand.

That said, nothing uses up calcium in large amounts that is not using alk.

I think I understand what you are saying.

I was just looking at it as a one time correction from 380ppm to 410ppm after a dosing pump failure.

A better question may be why calc would have dropped that much in the first place with so little actual alk demand.

 

[TheEngineer]

That said, nothing uses up calcium in large amounts that is not using alk.

A better question may be why calc would have dropped that much in the first place with so little actual alk demand.

Yes! Maybe I've got a bad hannah batch of alk reagent? I'll double check with my Red Sea Pro kit....brb

 

[TheEngineer]

Red Sea: 8.4 DKH
Hannah: 165 ppm (9.24 dkh)

Grumble grumble....

 

[Brew12]

Red Sea: 8.4 DKH
Hannah: 165 ppm (9.24 dkh)

Grumble grumble....

Aren't hobby level test kits wonderful?

FYI, I really dislike my Hanna ULR phosphorus test kit. I find it very finicky.

My Redsea and Salifert Alk tests read around 0.4dkh apart. I just note which one I use and try to keep it consistent test to test.

 

[TheEngineer]

I switched from Red Sea because the color change is so subtle. I have the phosphate checker too but don’t have anything to compare it against.

 

[Randy Holmes-Farley Verified Community Expert]

I think I understand what you are saying.

I was just looking at it as a one time correction from 380ppm to 410ppm after a dosing pump failure.

A better question may be why calc would have dropped that much in the first place with so little actual alk demand.

Yes, I agree. If real alk depletion is 0.06 dKH per day, calcium depletion is very, very slow.

 

[TheEngineer]

Whose stealing all my calcium!? Lol

I have a good bit of coralline growth but almost no coral.

 

[Randy Holmes-Farley Verified Community Expert]

Whose stealing all my calcium!? Lol

I have a good bit of coralline growth but almost no coral.

Still needs alk, at about 2.8 dKH for each 18 ppm of calcium.

 

[TheEngineer]

I’ll check calc with Red Sea too. Something has to be reading wrong.

 

[TheEngineer]

Let me also re-re-re-check my math on the alk dosing...It is running once every 360 minutes for 15 seconds. That's once every 6 hours which is 4 times a day. That's a total of 60 seconds run time. I dose 2mL per minute. So that means 2mL is dosed daily.

Yes?

 

[Randy Holmes-Farley Verified Community Expert]

Let me also re-re-re-check my math on the alk dosing...It is running once every 360 minutes for 15 seconds. That's once every 6 hours which is 4 times a day. That's a total of 60 seconds run time. I dose 2mL per minute. So that means 2mL is dosed daily.

Yes?

Sounds right. People often have different delivery than the rated pump spec., but not 10x.

 

[TheEngineer]

Red Sea calc is 370 ppm.

Hanna calc is 400 ppm

 

[TheEngineer]

Sounds right. People often have different delivery than the rated pump spec., but not 10x.

I sit next to the tank all day and I hear when the doser runs. It is definitely not running that long. I'm thinking of catching the doses for the next 24 hours and verifying.

 

[TheEngineer]

I have a lot less faith in the hanna calc test too. It's 100:1 in terms of sample to water volume and that concerns me.