Rising Alkalinity

[Randrew215]

Over the past few months I've been trying to clean up my tank parameters to try out some SPS corals. Brought phosphates to zero, nitrates to between zero and and 5 ppm, and set up an ato to keep sg constant. My trial SPS (purple cap) and my LPS corals are growing, so that's good. I top off with kalk and dose B-ionic daily, but my alk has been steadily rising while my Ca++ levels have been falling even though I dose in equal parts. Is this normal? Sg has stayed at 1.025, pH is always at 8.2, Ca++ has been as low as 360 and as high as 450 (I dose extra Ca++ in accordance w/ Randy Holmes Farley's article to bring back into range if low), but kH has steadily risen from 8.3 to 12.2. Is there an explanation for this? Test kits are not expired. Is there a point at which this becomes problematic for my tank or do I just stay the course? Tank is 90 gal w/ 29 sump and I change 15 gallons weekly. Thanks,
-Andy

 

[Gary Majchrzak]

do you perform regular water changes?

what salt mix are you using?

stop adding B-ionic alk supplement- only add B-ionic calcium. Get Ca and alk balanced.

It's okay to add only calcium if alkalinity is already high enough.

 

[Randrew215]

I perform 15 gallon changes weekly w/ IO. Switching over to reef crystals after this bucket runs out (probably after this week). I suppose that's what I'll do then is continue with the calcium and hold off the alkalinity until they are balanced, then go in tandem and see if the pattern continues. I'll update this thread if the problem continues.

 

[Gary Majchrzak]

you've figured out what's happening, right?

My suggestion would be to continue using IO and make up the difference in Ca using a liquid two part. It's very inexpensive to make your own liquid two part, BTW.

 

[tmz]

It has to be a dosing imbalance from the supplements or the salt or a testing error ,imo.
As calcium carbonate precipitates from biotic or abiotic precipitation more significant drops not increases in alkalinity relative to calcium will occur. For each 20ppm of calcium used a whopping 2.8 dkh/1meq/l or 50ppm of carbonate alkalinity is used in forming calcium carbonate.

Kh at 12.2 is a bit high . FWIW I prefer keeping it around !0dkh,. Keeping alk steady is very important for sps, ime, more so than ph which is ok in a 7.8 to 8.4/.5 range although I prefer it in the 8.2 to 8.3 range.

So, I'd stop dosing alk untill it was less than 11 dkh or even lower(7 to 11 dkh is an acceptable range). Calcium is ok north of 380ppm.
Checking magnesium might also be worth a look.

 

[tmz]

Footnote:The kalk plus bionic may be just too much alkalinity vs consumption in your tank. I'd try just the kalk for a while. How are you dosing it: drip, doser,how much at one time ,how much per day?

 

[Gary Majchrzak]

if one performs regular water changes with a saltmix low in calcium and high in alkalinity the two can get outta whack pretty quick................

 

[Randrew215]

I've been dosing 20 cc's/day of each component via 10 cc syringes (maybe 15 minutes apart). As dosing methods go, it's a little crude yet. I stopped dosing alk for now and will be testing Ca and Alk daily until I get and keep my levels balanced, at which point I'll consider dosing pumps. Gary, thanks for the heads up on the 2 part- I put in order in to BRS this morning (I'm sure there are even cheaper ways to compose it, but one step of complexity at a time). As of today KH came down to 11.4, Ca is 430. I'll look up the composition of RC and of IO, but I'm definitely switching over to it for now since the bucket is purchased and in my basement. I did just kalk (no dosing) for the month of November and Ca dropped to 330 and KH ~7 (not at home so don't recall offhand) despite the water changes. Thanks for the input!

 

[Gary Majchrzak]

jmo

jmo

I use IO for water changes. I change out a lot of water. IO usually mixes up somewhere around 10-11 dKH but batches may vary. Calcium and Mg usually requires a little bit of boosting and it's not a big deal IMO. If you bump up Ca in the new saltmix during preparation (before using it to do a water change) it won't throw levels in the aquarium off. Bumping up Ca, Mg or alkalinity can be done very easily and inexpensively.
BRS offers some great chemicals and instructions for making liquid two parts.
There are other even more inexpensive alternatives to explore when you're ready.

Anyone can appreciate the savings nowadays.

Tips: hot RO water will safely speed up preparation of the alkalinity supplement. Calcium chloride and Magnesium chloride generate heat when mixed into RO water (exothermic reaction).