Help APT Sky Plus - unexpected GH

[bradleysryder]

I recently setup an RODI unit and am planning to slowly transition my tank over to RODI water. I got the ubiquitous Brute 32 gallon bin to hold the water and remineralize and bring up to temperature for water changes. I have a small power head in the bin to circulate the water.

I want to target 6GH and 1.7KH, which according to the 2Hr dosing calculator was 22.1g (using 30 gallons of the 32 gallon bin).

I confirmed the water was 0 TDS before dosing APT Sky, and then carefully measured and dosed 22.1g. Now it is ~20 hours later and the KH seems to be spot on (2 drops on the API test kit), and the TDS is within the predicted range (~120), but the GH is in the 8-9 range (again, according to the API test kit)

Is some range of inconsistency expected with remineralizers, or am I likely having an issue where the minerals are not all dissolved or unevenly distributed in the water? Possible issue with my test kit?

Thanks for any help!

 

[BigWave]

I would think it would be spot on. After all it is a commercial product and there are guidelines and regulations.
Did you calibrate your test kits? There are tutorials around here somewhere to do so.
Um not quite sure but I do not believe APT Sky raises kH only gH.
RO water should be dang near 0 kH and 0 gH. Or very very low of both.

 

[Sb1415]

You could try checking the gh of the rodi water to confirm. My RO unit water has a tds of 6-7 and a gh of 1-2 atleast what the api kit says. @BigWave apt sky PLUS does raise both gh and kh, while APT sky just raises GH

 

[Dennis Wong]

I recently setup an RODI unit and am planning to slowly transition my tank over to RODI water. I got the ubiquitous Brute 32 gallon bin to hold the water and remineralize and bring up to temperature for water changes. I have a small power head in the bin to circulate the water.

I want to target 6GH and 1.7KH, which according to the 2Hr dosing calculator was 22.1g (using 30 gallons of the 32 gallon bin).

I confirmed the water was 0 TDS before dosing APT Sky, and then carefully measured and dosed 22.1g. Now it is ~20 hours later and the KH seems to be spot on (2 drops on the API test kit), and the TDS is within the predicted range (~120), but the GH is in the 8-9 range (again, according to the API test kit)

Is some range of inconsistency expected with remineralizers, or am I likely having an issue where the minerals are not all dissolved or unevenly distributed in the water? Possible issue with my test kit?

Thanks for any help!

If your weight calculations are correct, your GH/KH should be more or less spot on. Weight calculations based on chemicals are much more accurate than test kits. In fact, your weight calculations should be used to calibrate your test kit, and not the other way around. lol.

 

[bradleysryder]

If your weight calculations are correct, your GH/KH should be more or less spot on. Weight calculations based on chemicals are much more accurate than test kits. In fact, your weight calculations should be used to calibrate your test kit, and not the other way around. lol.

Ok, that makes sense. Thanks for the guidance! I am now suspecting my bin may be poorly measured and what I have is less than 30 gallons. I will re-check this tomorrow.

 

[ElleDee]

Yeah, the fact that TDS and kh are in agreement with your scale that suggests that your GH drops are to blame. If you haven't, check the expiration date on the bottle because I've definitely experienced odd readings past the date printed. I usually treat those kind of things as weak suggestions, but in this case the date meant something.

 

[Koan]

suspecting my bin may be poorly measured and what I have is less than 30 gallons

One of these can help