pH dropping -hello winter

[asylumdown]

Originally Posted by Reef Pilot

Hmmm, really?? I dose Seachem Reef Buffer (and have for a couple years) and keep my dKH around 8 or 9 (API, which is a single reagent test). I have in the past also tested with Elos or Salifert (can't remember which one), but the results were basically the same (just a finer granularity), so I went back to the API.

I have a lot of SPS in my tank and so far no problems. But now you have me worried. I may have to go out and buy another KH test kit. Is Seachem the one you recommend?

And I also have not tested pH for a year or more.

It's their Reef Status Magnesium test kit, comes in an obnoxiously large white plastic case with a red label. In addition to mag, that test kit does total alk and borate alk. You subtract borate alk from total alk to get your carbonate alk.

It's the only test kit that I've seen that has reagents to test for borate alk, all the other kits you just mentioned test for total alk only, so it's good that they agree. I'm just guessing, but I bet they make it specifically because of their reef buffer product.

Keep in mind that this was in... 2008 I think, so it's possible that reef buffer's formula has been changed and the ratio of borate to carbonate is different now. I was also a serious idiot back then and had no idea what I was doing, as referenced by the fact that I managed to get in to a situation where it was that out of whack. That was the same year I destroyed all of my pumps in a runaway precipitation reaction because I didn't know the first thing about reef chemistry. Looking back at pictures of that tank makes me cringe now.

I'd just be aware of it. Obviously if you've been doing what you're doing for that long things are working, but I'd still want to know how that total alk number broke down.

[asylumdown]

hmmmm, i might be out to lunch, API might test for carbonate alkalinity directly. I haven't used it in years, what colour is the reagent when it comes out of the bottle?

[Reef Pilot]

Originally Posted by asylumdown

hmmmm, i might be out to lunch, API might test for carbonate alkalinity directly. I haven't used it in years, what colour is the reagent when it comes out of the bottle?

It is pink first, and then turns purple/blue.

[asylumdown]

hmmm, then nope it's still measuring total alk, even though the box says it's measuring KH, which is not the same thing and is usually expressed in different units (meq/L). I can't figure out what indicator they're using, but what's in your bottle is basically just an acid and an indicator that changes colour once all the buffering capacity has been consumed and the solution suddenly turns acidic. Might be litmus.

I just searched reef central and found some posts from Randy Holmes where he found that the borate alkalinity test from sachem wasn't all that accurate so he recommends not doing it. If you've been doing what you're doing for two years I'd say you're probably fine. My case was likely an extra special case of being 'extra special'.

[Reef Pilot]

Originally Posted by Reef Pilot

It is pink first, and then turns purple/blue.

Whoops, I was thinking of my Ca test kit (2 part), which is also API.

The API KH test starts off blue, and then turns green/yellow and uses only 1 reagent.