Alk testing discrepancies

OrthoVet05 · Mar 10, 2019

Hey guys just picked up a salifert alk test today and switched from API. Have been shooting around 9 for the past 3 months using Randy’s 2 part dosing which has been pretty consistent. I am glad I picked up this test though because it read my alk as 10.2...

If I have been shooting for 9 and it’s slightly elevated which it likely has been 10.2 the whole time... should I just leave it be? I did have some minor burnt tips on a digi frag. I don’t plan on altering my current dosing which has been 50 ml per day of bicarbonate using recipe 1 of Randy’s.

Generally have nitrates around 5-10 ppm as what I can interpret from API.

Mixed reef 75 gal. Other parameters are normal. Thanks in advance.

Randy Holmes-Farley · Mar 10, 2019

Both of those alk levels can be perfectly fine if the corals have adequate nutrition. The nitrate should be adequate to prevent burnt tips from lack of nitrogen. Have you measured phosphate?

OrthoVet05 · Mar 10, 2019

Randy Holmes-Farley said:
Both of those alk levels can be perfectly fine if the corals have adequate nutrition. The nitrate should be adequate to prevent burnt tips from lack of nitrogen. Have you measured phosphate?

Hey Randy. Thanks for your reply. I do about once a week and it’s always the low or undetectable using API. Probably should invest in a better test.

I was doing flourish intermittently but a little shy with Sps. What are decent nitrate and phosphate levels for good nutrition? I have always heard such an array... 0-5, 5-10, 20-30 for NO3.

Randy Holmes-Farley · Mar 10, 2019

All of those are adequate. I’d personally target 1-5 ppm, or dose 1 -2 ppm nitrate per day if you have trouble attaining 1 ppm.

Randy Holmes-Farley · Mar 10, 2019

Make sure phosphate is not too low, although an api can test low enough to say it is too low.

OrthoVet05 · Mar 10, 2019

Randy Holmes-Farley said:
Make sure phosphate is not too low, although an api can test low enough to say it is too low.

So basically if I’m detecting 0.25 on api it’s probably ok?

Dkeller_nc · Mar 11, 2019

I'd personally recommend getting one of the Hanna ULR testers if you're keeping SPS and tracking phosphate. It's basically $50 + $9 for 7+25 = 32 tests, and each subsequent 25 tests is $9. Well worth having when keeping SPS, and a heck of a lot more precise and accurate compared to the "eyeball comparator" drop tests.

On the Salifert test for Alk, keep in mind that it's fairly easy to over titrate the sample, which will yield an overly high Alk reading. The color you want is kind of a lavender-pink, not the full-on orange that the sample will eventually change to if enough drops are added.