High calcium, low alk

[farfromsea]

Hi all I'm using the Hanna Marine Master. I *did* use RODI to zero the calcium--did not rinse with tap water--and the calcium in my tank is astronomically high. Did a 20-25% water change looks like I need to dose with washing soda. But to what level should I raise the alkalinity? Or just dose and test after five days?

Test	Before WC	After WC
pH	7.9	7.8
Alk (dKH)	8.4	9.2
Alk (meq/L)	3	3.286
Calcium	600	600
Mag	1255	1460
Nitrates ppm	25	27.8
Phosphate ppm	0.1	0.16

Per Randy's post I need to dose with soda ash due to the pH being below 8.2. Online seems to indicate that putting sodium bicarbonate aka baking soda in the oven at 300F will produce soda ash aka sodium carbonate. Will this ruin a nonstick pan?

I need to dose to get back into the good zone (red box) and I'm presuming the calcium will bind to the soda ash and not show on water tests? I've never dosed the tank ever so the high calcium isn't because of that...

I'm guessing I should add enough to raise my ~10 gallons of water by 1 meq/L and then test and see? Wait 24H and do a second dose if my ratio isn't any better?

 

[kharmaguru]

I'm suspicious something is a test error. I would think you'd be precipitating with those numbers. I'd actually do nothing but test for a few days and see what happens.

 

[farfromsea]

I'm suspicious something is a test error. I would think you'd be precipitating with those numbers. I'd actually do nothing but test for a few days and see what happens.

I tested four times the past few days because I was thinking the same thing (plus the machine suggested I did it wrong)

The only thing I can think is maybe the RODI water has trace calcium in it...but if it did wouldn't that be taken into consideration with the zeroing? I have no idea how I would mess it up that many times I've been meticulous and it prompts each step. I am using the microliter pipette for the aquarium water sample...

My fungia dropped dead and the tips of my voodoo magic acro have turned white so I feel like symptomatically something is wrong

 

[griss]

Have you tested a batch of newly mixed SW? I recently had a bad batch of salt (Coralife) that had high Ca which drove my Alk down.

 

[Jposch]

The marine master has a ±6% accuracy, so shouldn't be far off, assuming the reagent was good. Do you have an alternative test kit to verify? Hanna has a long history of bad batches of reagent from time to time.

 

[farfromsea]

Have you tested a batch of newly mixed SW? I recently had a bad batch of salt (Coralife) that had high Ca which drove my Alk down.

I will test the water today. That is a good idea. The water is from the LFS since I haven't managed to set up RODI in my rental yet

 

[farfromsea]

The marine master has a ±6% accuracy, so shouldn't be far off, assuming the reagent was good. Do you have an alternative test kit to verify? Hanna has a long history of bad batches of reagent from time to time.

I think the only other one available to me is the API kit from the store or a friend! Good to hear about the accuracy. I figure a photometer these days has to be pretty accurate given how far optics has advanced

All 4 times it was the same hue of blue to the naked eye. I was reusing the disposable pipette because I hadn't bought any and that is bad for the environment... but I don't think enough residual calcium would hide in it to make my calcium *that* bad...

 

[Jposch]

Don't use api calcium. Api is known to be accurate, but imprecise. (Always the same wider range result) but the calcium kit...that one is trash. The hanna magnesium checker and marine master magnesium, I wouldn't use. At 1500ppm, the accuracy and resolution combine give a ±300ppm range! 1500 actual could show as 1200-1800. Or anywhere between. I prefer salifert for alk, calcium, phosphate and magnesium. For po4, I use a hanna checker with salifert reagents and do a little math. More consistent than the hanna sachets, and reading salifert by the chart at typical po4 is difficult. Its also like 10 cents cheaper per test. Lol also can skip the countdown.

 

[farfromsea]

Don't use api calcium. Api is known to be accurate, but imprecise. (Always the same wider range result) but the calcium kit...that one is trash. The hanna magnesium checker and marine master magnesium, I wouldn't use. At 1500ppm, the accuracy and resolution combine give a ±300ppm range! 1500 actual could show as 1200-1800. Or anywhere between. I prefer salifert for alk, calcium, phosphate and magnesium. For po4, I use a hanna checker with salifert reagents and do a little math. More consistent than the hanna sachets, and reading salifert by the chart at typical po4 is difficult. Its also like 10 cents cheaper per test. Lol also can skip the countdown.

. My understanding is a 5% accuracy with a 5 ppm resolution? Idk how that is 300ppm? So approximately 60-75 ppm within actual... I thought the 5 ppm resolution just means it can tell you it is 1200 or 1205 but not 1202 or 1203 etc

 

[Jposch]

. My understanding is a 5% accuracy with a 5 ppm resolution? Idk how that is 300ppm? So approximately 60-75 ppm within actual... I thought the 5 ppm resolution just means it can tell you it is 1200 or 1205 but not 1202 or 1203 etc

5% not 5 ppm. 1200×5%=60ppm and and then add the 5ppm on top of that for a 130ppm range.

 

[Jposch]

I'd have to look at the exact specs, but if what you said is right, then 5% of 1200ppm isn't 5ppm. I just remember it was more than the 50ppm range of salifert, by ALOT.

 

[farfromsea]

I'd have to look at the exact specs, but if what you said is right, then 5% of 1200ppm isn't 5ppm. I just remember it was more than the 50ppm range of salifert, by ALOT.

I think they changed the reagent for the Mag test sometime around 2022? But yeah 5% would be a 60-75 ppm range of accuracy. I would be super annoyed if it is off by 300 ppm. I was hoping to use the Marine Master for all the tests because I like the digital tracker and simplifying my efforts

 

[Jposch]

They fixed the reagent issue before they announced the new marine master. I still get spotty results for no3 and po4 with the HR no3 and ULR PPB checkers unless I use api and salifert reagents (respectively) instead. Consistency is very important. Often more than precision.