Lowering high alk in SPS Dom tank

[triggerjay]

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!

 

[triggerjay]

Oh, I have as of yesterday cut off kalk supplement as well.

 

[markalot]

IMO and limited experience turning all dosing off and letting it fall naturally is usually the best method. I would target 7 or 8 since that's what blue bucket mixes at, but just my opinion.

 

[downbeach]

Make sure your salt mix is thoroghly mixed before using. Make sure of the accuracy of your SG, if its off you could be adding too much salt mix and by extension too much Ca Mg and Alk to your make up water. 13dKH seems a little high for plain IO, I would expect something around 10 or 11dKH @ a SG of 1.026(35ppt).

 

[Mock]

imo experience turning all dosing off and letting it fall naturally is usually the best method.

+1

 

[triggerjay]

Good plan mark..but what about water changes??

 

[markalot]

Good plan mark..but what about water changes??

I would not do any changes until it's down closer to 8.

 

[triggerjay]

I mix salt by weight, then double check SG. It's always been 1.026. I mix salt in RO/DI and mix for 24 hours with a power head. IO is 1lb 8oz to 5 gallons RO/DI for SG of 1.026. Params on mixed water after 24hr are:
Calcium 420
Mag 1300
Alk 13!
PH 8.1

I also shake I/o bag before each use to insure uniform results due to settling. I still want to perform my weekly water changes, but using blue bucket. Question is if I don't raise alk in wc water it will be 7-8ish.. And potentially shock the system. Sooooo... I will need to supplement alk somewhat in WC water to below tank alk, but not TOO FAR as not to shock anything. I'm thinking start at 11 or so alk on a 10G WC.. Total system volume is ~45g.. So that will be ~25%. Dilution I'm guessing would be around .5dkh alk? Should be a safe weekly drop? Then as levels SLOWLY drop I will lower ALK in WC water slightly until I reach target of 8-9ish? Does this sound safe?

 

[triggerjay]

Reasoning on still wanting to do WC is because I have a small system and need the extra nutrient export to maintain ULNS. I over skim with a bubble Magnus curve 5 and dose vinegar, but see the corals respond well with the water changes..

 

[triggerjay]

Make sure your salt mix is thoroghly mixed before using. Make sure of the accuracy of your SG, if its off you could be adding too much salt mix and by extension too much Ca Mg and Alk to your make up water. 13dKH seems a little high for plain IO, I would expect something around 10 or 11dKH @ a SG of 1.026(35ppt).

My last bag was 9dkh spot on every time.. It's this new bag..13dkh