Alk in SPS Dom tank

Triggerjay · Jun 15, 2015

Hello. Looking for advice. I have a 37g cube with a 10g sump. I have been using IO for 10g weekly water changes. The last bag I purchased mixed at 13dkh alk. I also dose kalk for makeup water. Cal runs 450, and mag I supplement to 1350. In the last week or so I have noticed a little STN on my green stylo first, then on one of my acros. I just got a Red Sea blue bucket to lower alk. Question is, how should I go about this? My goal is alk of around 9, but I know I should take it slow. My thoughts are to try to drop it about 0.5dkh a week. If I mix my 10g water change (approx 25%) and set alk 2dkh lower than the tank with my weekly water change. Would this be a safe change? Can I go faster than this? And is my math guesstimate correct? Thanks in advance!

Oh, I also stopped kalk dosing 2 days ago.

Randy Holmes-Farley · Jun 15, 2015

Instead of changing salts, which will have little impact on alkalinity, I'd just reduce or stop the limewater (kalkwasser).

What is the tank alkalinity? Is it also 13 dKH?

Is this a ULNS (ultra low nutrient system) tank?

Triggerjay · Jun 15, 2015

Randy, Forgot to mention.. My IO is mixing at 13dkh!!!!! That's why I'm switching to Red Sea blue bucket. Alk is supposed to be 8ish. Even before the high alk salt/kalk my tank didn't consume alk between water changes. I also have two part and have never had to dose alk part. I used kalk to increase PH.

Triggerjay · Jun 15, 2015

And yes, tank alk is 13. I would like to say it's ULNS. I over skim with a bubble magus curve 5, and dose vinegar

Triggerjay · Jun 15, 2015

You can tell when I started using this new bag..

Randy Holmes-Farley · Jun 15, 2015

OK, I'd stop the limewater until the alk declines to where you want it.
A 10% water change with 8 dKH salt mix will drop alk by 0.5 dKH. You very likely add more than that every day with the limewater.

Triggerjay · Jun 15, 2015

Ok that was the ratio I was looking for. I had to obviously switch salts (or bag) due to the high alk. I'll keep an eye on things with no kalk and 8dkh water changes and after alk reaches a decent level will start to supplement as needed. Thanks Randy.

Triggerjay · Jun 15, 2015

Oh, the graph is the trend from my water change water.. Not tank params.

Randy Holmes-Farley · Jun 15, 2015

Triggerjay said:
Ok that was the ratio I was looking for. I had to obviously switch salts (or bag) due to the high alk. I'll keep an eye on things with no kalk and 8dkh water changes and after alk reaches a decent level will start to supplement as needed. Thanks Randy.

I wouldn't conclude you had to change salts. You just had to stop supplementing so much alkalinity. Salt mixes do not drive the final alkalinity in SPS tanks any more than the gas in the car when you buy it determines how much gas is usually in it.

That said, switching salts is unlikely to hurt anything.

Triggerjay · Jun 17, 2015

But when you start with an alk of 13dkh just from the salt mix alone, I would say it's time to rethink it. I cut off the Kalkwasser two days ago and I did a 10g water change with the Red Sea blue bucket salt yesterday. Red Sea tested at 8dkh. Tank alk is now 10dkh.

On another note, even before I was dosing kalk, and before my bad bag of salt, I never noticed an alk depletion. The tank used to hold at 9dkh without supplementation. I would however see calcium drop and only added part 2 of my 2 part. I guess my weekly water changes was enough to hold alk at the steady 9. My previous bags of IO tested at 9dkh when mixed. I started using Kalkwasser at 9dkh which didn't really have much of an impact on alk, but drove my PH up to 8.4 from 8.0-8.2ish. At this point I started to see great growth from my SPS. I also dose Kents tech-m and try to aim for 1350-1500 range. I would say the high alk IO, in combination with kalk drove my tank up. I only saw an impact on two corals. First it was a green stylo, then one of my acros within about 24 hours of each other.

The stylo is already showing signs of improvement, but the acro continues to STN. All my other corals including various other acros and a pocillapora never showed any signs of distress. montipora's all look great too. I am hopefull that I caught it in time.

In conclusion, I feel that my old IO salt, along with Kalkwasser was a good fit for my tank. It wasn't until I acquired this new bag that I saw issues. I tested my NSW and knew the alk was 13dkh, but with no other salt on hand I threw caution to the wind and used about 40 gallons worth over the course of a month, never thinking to cut off the kalk.

Thanks for your input Randy! I have read just about every article you have published more than once. I have been in the hobby for about 15 years or so and stepped out for about 5 years and just getting back into things.

Randy Holmes-Farley · Jun 18, 2015

Triggerjay said:
In conclusion, I feel that my old IO salt, along with Kalkwasser was a good fit for my tank. It wasn't until I acquired this new bag that I saw issues. I tested my NSW and knew the alk was 13dkh, but with no other salt on hand I threw caution to the wind and used about 40 gallons worth over the course of a month, never thinking to cut off the kalk.
.

Thanks!

FWIW, I use just normal IO and limewater.