Testing Conundrum

Jdzzl03 · Jun 22, 2022

Hey Everyone!

I wanted to get your take on test kits. I recently was fortunate to acquire a Mastertronic from BRS. I had a LFS help setup and calibrate the unit and it is using Red Sea pro solutions for Ca. It is currently reading at 561 and I think it is not quite calibrated correctly but thats not the reason for this post. While we were testing baselines to get everything setup the tech mentioned that the Hannah Ca checker (I currently have all of the Hannah testers and have been using them for a number of years) may not be the most accurate specifically for Ca and recommended the Red Sea Pro Ca kit. So I checked Ca yesterday with Hannah 2x and both readings were within 5ppm of each other (478 and 483). I tested again today with Hannah (480) and then Red Sea 2x. Both Red Sea tests came out at 380. Taking the Mastertronic reading out of it, what is your opinion on these kits? My Acros are stable but not really growing all that much. All of my other corals, (acans, shrooms, zoas, leather, digi, favias, platys, Pocillopora etc) are looking great. I am not chasing perfect parameters but am looking for a more stable calcium reading so I can properly calibrate my Mastertronic, dose Ca if needed, and get my Acros to take off like all of your awesome tanks. I appreciate any help in advance!

Alk is 9.4 and been rock solid
Mag is somewhere between 1250 and 1300
Salinity is 1.26
PO4 .003mg/L
NO3 is 4.82 (working on getting that down with WCs and modifying my feeding schedule)
Temp is 79

A_Blind_Reefer · Jun 22, 2022

My vote is to just pick one and stick with it. I like the Red Sea Ca kit, but personally know the actual, true value may be off. I care more about it staying at value x. I always back it up once in awhile with a different test kit after establishing a baseline difference between the results.

ZombieEngineer · Jun 22, 2022

I would just get a multireference solution and find out which one is actually correct.

Jdzzl03 · Jun 22, 2022

Ah thanks, I hadn’t thought of that. I got burned with the trident’s calibration solution and overall experience (hence the switch to MT) but I may give that a shot.

arking_mark · Jun 23, 2022

A couple of thoughts here with Ca measurements.

Our hobby testing kits are pretty inaccurate. Hanna is probably +/-20ppm at best.
Alk measurements are much more accurate.
For most practical purposes, Alk/Ca are taken up almost equally. Depending on YOUR tank inhabitants, Ca uptake will be slightly slightly less. Each tank is slightly different.
Ca is much more readily available in seawater and it's actual value isn't that important as long as its in a rangle you feel comfortable with.

For the above reasons, I dose balanced Alk/Ca and use a quality ICP test every 6 months to adjust Ca with unbalanced two part dosing.

Jdzzl03 · Jun 23, 2022

Thanks @arking_mark! Yeah I don’t think my tank is necessarily at the point where the Ca uptake is significant. I have a medium sized Deresa clam that has been growing well but the majority of my SPS are frag sized. I’m dosing 80ml of alk per day which has kept my alk very stable. I was dosing Ca but due to faulty trident readings stopped and went back to 15% weekly water changes until I get my Versa dosing pumps to switch to 2% daily AWCs. My goal is to get my testing / reporting rock solid so I have the right info going forward as my Params naturally change due to growth. I really appreciate all the help and feedback!

ZombieEngineer · Jun 23, 2022

Jdzzl03 said:
Thanks @arking_mark! Yeah I don’t think my tank is necessarily at the point where the Ca uptake is significant. I have a medium sized Deresa clam that has been growing well but the majority of my SPS are frag sized. I’m dosing 80ml of alk per day which has kept my alk very stable. I was dosing Ca but due to faulty trident readings stopped and went back to 15% weekly water changes until I get my Versa dosing pumps to switch to 2% daily AWCs. My goal is to get my testing / reporting rock solid so I have the right info going forward as my Params naturally change due to growth. I really appreciate all the help and feedback!

Get a DOS not a versa. It's cheaper and more reliable for AWC and integrates better with your apex. I have a DOS that has been doing AWC for 8 years and all it needed was one head replacement about 4 years in. Still works great to this day.

arking_mark · Jun 23, 2022

Jdzzl03 said:
Thanks @arking_mark! Yeah I don’t think my tank is necessarily at the point where the Ca uptake is significant. I have a medium sized Deresa clam that has been growing well but the majority of my SPS are frag sized. I’m dosing 80ml of alk per day which has kept my alk very stable. I was dosing Ca but due to faulty trident readings stopped and went back to 15% weekly water changes until I get my Versa dosing pumps to switch to 2% daily AWCs. My goal is to get my testing / reporting rock solid so I have the right info going forward as my Params naturally change due to growth. I really appreciate all the help and feedback!

Again Ca and Alk uptake is almost equal in every tank...they are not consumed separately. For every 1dKH consumed roughly 7ppm Ca is also consumed. For all hobby grade test kits, 7ppm is in the error range. So to see Ca uptake, you probably need at least 3dKH of consumption...