Monitoring ALK in Lieu of CAL for SPS and LPS Growth Rates

[Adamantium]

Hi all, I recently gotta Hanna checkers for ALK and CAL. Unfortunately, the CAL checker is hugely unreliable. Totally all over the place. I'm getting 445, 365, 405, 385, all within a few minutes of each other. It's also a pain in the *** to do.

The ALK checker, on the other hand, has been spot on, always within just a few PPM.

I know that people say to monitor your CAL usage day to day to determine how much 2 part to dose, but is it possible to determine the same with ALK instead? The test is way more reliable, and very accurate, down to 1-2 PPM. After doing some math, my current KH is 9.016.

Any insight would be greatly appreciated! Thanks!

[wfv57]

I have monitored both for years. I have indeed found that primarily monitoring alkalinity with a weekly check of calcium and magnesium has worked fine.

[mcgyvr]

Yes..
Calcium consumption is about 18-20 ppm for each 1 meq/L or 2.8 dKH of alkalinity
Note that in a perfect world the consumption is as stated above..
This isn't a perfect world so spot checking cal every once in a while is a good idea but many people dose based on that ratio above..

Mag is also important to monitor as
Magnesium's primary importance is its interaction with the calcium and alkalinity balance in reef aquaria.
........
Without the magnesium, the abiotic (nonbiological) precipitation of calcium carbonate would likely increase enough to prohibit the maintenance of calcium and alkalinity at natural levels.

[Adamantium]

Thanks for the insights!

Wow, that's quite a significant drop in Alkalinity for only an 18-20PPM drop in Calcium.

So, if I'm understanding this correctly (which I'm probably not), if I check my ALK one day, and find it's 9.8, and then the next day it's 7, my tank used ~20 PPM of CAL that day?

That just seems like such a dramatic drop in ALK. Is that pretty normal, though?

[Vinny Kreyling]

ALK should be THE stable parameter.

[mcgyvr]

Thanks for the insights!

Wow, that's quite a significant drop in Alkalinity for only an 18-20PPM drop in Calcium.

So, if I'm understanding this correctly (which I'm probably not), if I check my ALK one day, and find it's 9.8, and then the next day it's 7, my tank used ~20 PPM of CAL that day?

That just seems like such a dramatic drop in ALK. Is that pretty normal, though?

Thats what it is because that is the ratio of each in the formation of calcium carbonate.

There are times when that consumption/rate is not what I stated..
All the learning about it here in this link..
http://reefkeeping.com/issues/2004-12/rhf/index.php
In general though you are usually safe enough to dose it in that ratio..

But again.. Spot checks are a good idea as this isn't a perfect world..

[hkgar]

Get the Salifert test for Calcium. I use Salifert also for Mag. Either Hanna or Salifert for dKH work very well.

I test Alk almost daily and ca and mag weekly.

[Uncle99]

ALK should be THE stable parameter.

Yes, oh yes, oh yes, that be solid advice!

[Uncle99]

Get the Salifert test for Calcium. I use Salifert also for Mag. Either Hanna or Salifert for dKH work very well.

I test Alk almost daily and ca and mag weekly.

+1 for the Salifert CA test (I too no longer use my Hanna)
And
I use the Salifert for phosphate as well (no longer use the Hanna)

[hkgar]

+1 for the Salifert CA test (I too no longer use my Hanna)
And
I use the Salifert for phosphate as well (no longer use the Hanna)

I love my Hanna Phosphorus checker.

[pisanoal]

I love my Hanna Phosphorus checker.


Same... I find the Salifert isn't senesitive enough.

OP: the reason your calcium reading is swinging so much is that the hanna test only uses .1 ml of tank water. If you are off by just a little bit, that is a huge error percentage. You have to be meticulous about your measurement, then you can get decent results. Even then, it's easy to be off 10ppm or more from measurement to measurment.

I too found it a pain to use, even though i was mostly getting repeatable results. I switched to salifert. But i only spot check it as others have said.

[Adamantium]

That's what I've been hearing, so I picked up a 100ul pipette from Amazon. Hopefully that helps me get more reliable results.

[Uncle99]

Salifert is sensitive enough to ensure that I remain in the range, whether it's 420 or 426 or 433, it's really not important. I can test calcium in 30 seconds at 1/4 the price of Hanna which takes 5 times the time. It still have it, but sits in the box.
Now Alk, yes, yes, I love this checker.....here I want to be absolutely consistent.

Same with phosphates, if it's .05 or under, I am happy, and again, way cheaper, and way faster.

To each his own

[Adamantium]

Yup, I'm loving the ALK checker. Here's hoping the new pipette helps, but to be safe, I did order Salifert CAL, MAG, and ALK. Now I have three different sets of reef test kits lol

At least now I can triple check my results.

[mrg02d]

I test alkalinity daily and the others (calcium, magnesium) on the weekend. Alkalinity is the only one that I watch like a hawk. The others just need to be “in range”.