Test kit inconsistencies

jordimex · Apr 27, 2018

i tested my water today and alkalinity gave me a bit of a headache not sure what to trust or what to follow.

Red Sea alkalinity pro test has my alkalinity at 6.2 (tested twice)
KH director 7.6
Hanna 7.1
Salifert 7.4 im not sure what test should i follow although the kh director hanna and salifert are preety close together

any advice

Randy Holmes-Farley · Apr 28, 2018

With that spread, I’d ignore the Red Sea and call it 7.5 dKH.

scardall · Sep 23, 2018

I have a similar issue myself.
Hanna 6.1 dkh
ELOS 6.5 dkh
Salifert 8.0 dkh

I'm inclined to throw out salifert results. I have an addition concern as well. I does BRS liquid Soda Ash using BRS calculator for amt. needed to hit target. I dosed an amt that would give me 8.0dkh from 5.3dkh.(120ml) Tested 2 hours latter and got 6.3 dkh. does the same amt again and a couple hours latter I had a LFS test water with a salifert test kit. I was told it was 8.0-8.5 dkh.

Can I assume that 120ml of soda ash mix = a 1 dkh increase and if I added an addition 120ml thus 240ml total that dkh would increase by 2?

Randy Holmes-Farley · Sep 23, 2018

It is true that doubling the dose will double the expected alk boost of any additive.

That said, we can't calculate amounts of expected rises without knowing the total system water volume (estimated).

scardall · Sep 23, 2018

Randy Holmes-Farley said:
It is true that doubling the dose will double the expected alk boost of any additive.

That said, we can't calculate amounts of expected rises without knowing the total system water volume (estimated).

The amt. I dosed is based on 65g of total water.

Randy Holmes-Farley · Sep 23, 2018

That's the correct calculation for a solution that is made correctly to be my DIY #1 (which is what BRS uses).

It is possible the solution was more dilute than you thought, that some was precipitating in the system (by not mixing in fast enough, etc.0 or that it was still getting distributed (for example, with a long, extended sump/refugium system), or the testing was off.

scardall · Sep 23, 2018

Randy Holmes-Farley said:
That's the correct calculation for a solution that is made correctly to be my DIY #1 (which is what BRS uses).

It is possible the solution was more dilute than you thought, that some was precipitating in the system (by not mixing in fast enough, etc.0 or that it was still getting distributed (for example, with a long, extended sump/refugium system), or the testing was off.

I mixed 2 cups to 1 gallon of RODI water. This time in batches of 1000ml till water totals 1gal I mixed ash to water with a magnetic stirrer. I added solution to overflow to sump. Tank has 2 power heads and 2 pumps with a T fitting attached. for flow, not counting return water flow. I did wait 2 hours after 1st dosing (tested) and 22 hours after 2nd dosing . I'm repeating today around 4 hours after dosing to see if it is a time based distribution issue. I'm thinking my powder to water ratio is wrong. If so next batch mix, I'm thinking should be 4 cups instead of 2 cups of soda ash.

Your Thoughts on this plan??

Randy Holmes-Farley · Sep 23, 2018

scardall said:
I mixed 2 cups to 1 gallon of RODI water. This time in batches of 1000ml till water totals 1gal I mixed ash to water with a magnetic stirrer. I added solution to overflow to sump. Tank has 2 power heads and 2 pumps with a T fitting attached. for flow, not counting return water flow. I did wait 2 hours after 1st dosing (tested) and 22 hours after 2nd dosing . I'm repeating today around 4 hours after dosing to see if it is a time based distribution issue. I'm thinking my powder to water ratio is wrong. If so next batch mix, I'm thinking should be 4 cups instead of 2 cups of soda ash.

Your Thoughts on this plan??

No, 4 cups won't dissolve and is not the recipe.

I'd suggest spreading out the dosing over time and not all at once. 3 dKH at once is too much at once. If that's what you did, the pH spiked and you may have precipitated it back out.