Why alk & not Ca

[Daddio]

In preparation for a doser, I have been doing daily tests. I have tested for about 9 days in a row to try and get a good sample size.

My question is, my alk is dropping .2 meg/l per like clockwork but my calcium holds very steady, if not jumping back and forth - 430>410>420>410, etc.

I thought it was maybe because the alk was low to begin with so it adjusted all my levels back to "ideal" and started over.
My mg is at 1300 and I rarely have to dose that, maybe once or twice a month.

If I go back through my logbook and extrapolate 2 week periods of time, looks like Ca was dropping about 5 per day in the past ( not testing every day).

I do only have a few LPS coral, and lots of shrooms, zoas, leathers, etc -no SPS. I did add 40 lbs of cured rock recently to my sump to seed it for my rebuild.

I need to dose alk again as it has dropped to 2.6. Any ideas why this is happening or just adjunct my alk back to optimal level and give it time...

 

[kpiotrowski]

you got it! aquariums don't use alk and ca in equal proporation...at least the way we test for it. alk and calcium do have a very exact relationship and bind to eachother in a predictable proportion but it is not reflected as equal amounts on our test kits.

I try to tell people ALK is number one to dose and keep constant! cause it is!

 

[Daddio]

Thanks. I usually only test every couple of weeks and thought I was going crazy... I will let it go for now and look at the results in longer stretches of time for the ca. When I hook up my doser, I'll try very low amounts of Ca and then try to dial it in.

 

[TriggerThis]

I have a 100gal and a bunch of random corals.
My alk drops like a rock over time
It drops soo much I lost corals due to the fluctuations.
My mag would also never get above 1230 unless I just dumped bottles in.
I was dosing 20ml of alk and 10 of calcium every day but still not getting good numbers.
Recently bought a bubble magus doser and wow was I under dosing.
I have it almost dialed in.
I'm dosing over 40ml of alk every day and 32ml of calcium
I'm also dosing over 40ml of mag to keep it at 1400.
The point is every tank is different and some need a lot of alk.

One last thing, a lot of salt mixes are low in alk too.
Last water change I did with reef crystals the dkh was at 7 for the mix. My tank is at 9.6 right now. I had to dump half my alk bottle in the bucket to get it up to the tanks levels.
So your water changes could be dropping your numbers a lot too

 

[DSP]

I have a 100gal and a bunch of random corals.
My alk drops like a rock over time
It drops soo much I lost corals due to the fluctuations.
My mag would also never get above 1230 unless I just dumped bottles in.
I was dosing 20ml of alk and 10 of calcium every day but still not getting good numbers.
Recently bought a bubble magus doser and wow was I under dosing.
I have it almost dialed in.
I'm dosing over 40ml of alk every day and 32ml of calcium
I'm also dosing over 40ml of mag to keep it at 1400.
The point is every tank is different and some need a lot of alk.

One last thing, a lot of salt mixes are low in alk too.
Last water change I did with reef crystals the dkh was at 7 for the mix. My tank is at 9.6 right now. I had to dump half my alk bottle in the bucket to get it up to the tanks levels.
So your water changes could be dropping your numbers a lot too

Reef crystals alkalinity is real high way above 7, Did u mean standard instant ocean? It's alk is around 7, And good to hear your liking the doser because that's the one I may end up switching to.keep me updated please!

 

[Justdrew]

My last box of IO is reading 12dkh for ALK. Many others have reported the same numbers.

 

[b_rad_G]

Ca and alk are used in a 1 meg/l to 17-20 ppm ca. So if you drop .2 meg/l then can should only drop by 3-4 parts. There is no way a hobby grade test kit can accurately test this so I would suggest saving your kits and only test every 4 days...or longer. Then you will have a significant drop that you can measure.

 

[Daddio]

Thanks brad... It thought over 9 days or so I might see a trend... I am not touching anything until Sunday... It's hard to do ( like mot peeking at Christmas)