Kalk via ATO or Doser

wcharon · Nov 4, 2015

Hi Randy and Forum Experts...

I need you to share some of your expertise and bring me some light. I am having problems trying to stabilize my ALK and Calcium parameters.

I got some bleached Acros and i am sure it was because a raise in my ALK from 7.6 to 8.3 in a 24 hour range. Calcium is 440 amd Mag is 1380.

I was using KALK thru ATO at a strength of 2 TBS per gallon. Installed an APEX and calibrated the PH probe and also double checked it with Salifert. The PH was raising up to 8.5 so i started to reduce the KALK strength and i am now at 1 1/8 TSB per gallon. The PH was great getting to 8.35 but my evaporation has get crazy and for the past 2 days it is reaching 8.46 and i assume this raised my ALK to 8.3 causing the bleach in corals. in 2 days.

Sorry for the long history but wanted to explain well the situation. I know i should not worry to much with the PH readings but it is also affecting the ALK levels.

My questions are:

1. Should i keep reducing the KALK strength until i get the sweet point via ATO?
2. Should i use better the Doser to dump the KALK and get more control of the KALK?
3. I actually also use the Doser for 2 part dosing.

Thanks in advance and as you can see i want to stabilize the most possible and trying to avoid equipment dependencies... Let me know if you want me to post the PH graphs so you can see the bouncing.

Randy Holmes-Farley · Nov 5, 2015

I'd be somewhat surprised if an alkalinity rise from 7.6 dKH to 8.3 or the pH at 8.46 caused bleaching. I know it is currently very chic to say that stability is ultra important with SPS, and to some extent it is probably true, but I think some folks may carry that beyond the limits of what the data show. Many people keep SPS with just once a day dosing of a two part, and their alk certainly changes as much or more every day than yours did. That doesn't prove the alk didn't cause the bleaching, but I'm just reluctant to simply accept that it did.

How are you making your limewater (kalk)? 2 teaspoons per gallon of freshwater is about the limit of solubility, so 2 tablespoons per gallon should be leaving a lot of excess solids. That's OK as long as you are not dosing solids too.

Using a dosing pump for limewater might be helpful. I do not use one for mine, but I also do not presently keep SPS.

How much does the pH spike up with each trigger of the ATO?

wcharon · Nov 5, 2015

Thanks Randy

At this moment i am only using 1 1/8 Teaspoon Kalk per gallon. The PH spikes something around .2 when the ATO refills. Correct is Teaspoon. Sorry.

By the way i was checking my logs after i wrote last night and maybe this coincides with your point that may ALK or PH is the culprit. I do maintenance on Saturday mornings and i refreshed the GFO and Carbon medias as i starting to see some hair algae. As usual i only put around 8 Teaspoon in the reactors but this time i put more flow thru them.

Maybe i starved the coral from lack of nutrients too fast?????

wcharon · Nov 5, 2015

Randy ... do you think my assumption is correct???

Randy Holmes-Farley · Nov 5, 2015

That is possible, yes. More often it results in pale corals rather than actually bleached, but IMO it is more likely the cause of bleaching than is that alk rise.

Backing off on the amount of solids in the limewater (as you did) is also appropriate, unless the evaporation is going to drop back again.