Alk swing?

Ryan15236 · Nov 7, 2015

Usually my alk sits around 7.6 dKH. I usually test on Friday then again on Sunday and let the tank run on cruise control Monday through Thursday...well when I test my alk Friday I got 8.7 dKH. I thought this unusually but didn't think much of it because I added some really high saline water to the tank Sunday for a bost in salinity which took it from 1.024 to 1.025. Well today I noticed a couple of bleached tips on my ORA green birdsnest so I test alk again and now I'm getting the usual 7.7???? Did my alk really swing 1.1 dKH overnight? If so why? I use kalk in ATO. I am still trying to dial it in. I am currently at 1/2 tsp per gallon. All other corals including sps look fine and my sour apple BN looks fine too

Randy Holmes-Farley · Nov 7, 2015

You certainly could use 1 dKH overnight. Many people use more than 2 dKH per day.

The salinity boost probably accounted for about 0.5 dKH boost.

But test kit errors are also fairly common.

Ryan15236 · Nov 7, 2015

I only have like 13 small sps frags and haven't been using near that much alk.. I'm going to assume their could be a 0.2 error either way in the testing kit so I could have gotten something more like 8.5 yesterday and 8.0 today possibly...I just don't know how my alkalinity shot up that high anyways.

What should I do? I am about to do a small 3 gallon water change just because it's water change day. Should I leave alk alone and stay at the same 1/2 tsp per gallon potency and just keep testing?

Will the birdsnest be alright? All others look great. Which are green slimer, purple acro,rainbow Mille, green acro, tri color granulosa, 3 stylos and a few others so it just baffles me the BN is the coral unhappy when it's supposed to easy to keep!

Randy Holmes-Farley · Nov 7, 2015

I'd just stay the same and test alk over a few days. That tends to smooth out testing issues by having more data points before responding to a change that might not be rea

In terms of the coral, it's hard to know what caused it.

How low are nutrients? If it is a ULNS tank, raising alk can be an issue.

Ryan15236 · Nov 7, 2015

Alright and my nutrients are pretty low but idk what constitutes the ultra low nutrient system. I only have 3 fish (2 clowns and firefish) and about 25 corals in a 125 gallon tank. It has a skimmer rated for 240 gallons. I feed corals 1-2 a week and fish twice a day. Nitrates are 0ppm on api test.

Randy Holmes-Farley · Nov 7, 2015

Ryan15236 said:
Alright and my nutrients are pretty low but idk what constitutes the ultra low nutrient system. I only have 3 fish (2 clowns and firefish) and about 25 corals in a 125 gallon tank. It has a skimmer rated for 240 gallons. I feed corals 1-2 a week and fish twice a day. Nitrates are 0ppm on api test.

It's hard to know how low your nitrate is, but it could be low enough.