Alk and Calcium Issues

aileen · Dec 25, 2017

So my tank is a little over 2 months old. 80g display (48x24x16). 150g Rubbermaid sump. 100lbs of LR. Maybe 160g total volume. I use zeobak and zeostart as directed. I have a K1 Kalk Stirrer dosing Kalk in my ATO with RODI and use anywhere around 1g to 2g of freshwater dosed with Kalk per day. Now, I fill my K1 about 1/3 of the way with Kalk at all times so it’s loaded. I’ve had consistently had alk at anywhere between 6 and 7 and calcium anywhere from 410 - 420 for the last month. I use sailfert test for calcium and Hanna for alk. My current coral list is about 12 lps and maybe 12 sps (montis, acros and millis). My ph was hovering anywhere between 7.7 and 7.9 until I added a CO2 skrubber and now I’m anywhere from 7.9 to 8.1. Due to what I considered to be suboptimal alk and calc levels (I’m shooting for 8 DkH and 440 calcium) I decided to dose 2 part and get there. FYI mag has been around 1250 to 1300 consistently.

I’ve been literally dosing 100 ml of alk and calcium per day for a week and my alk has at best been 7.1 and calcium 430. Calcium isn’t really that bad but the alk is puzzling.

I used to have a 250g system and had mostly sps 25 or so colonies and I got by on Kalk alone because my evap rate was literally 4g or so a day, but that was a diff house and the hvac system was very different.

Does it seem odd to be dosing so much alk and calcium per day 100ml or so? It’s not precipitating anywhere I can see, I don’t have a sandbed and there are no chunks of precipitate in the sump. It’s just puzzling me and while I’d like to think of myself as a skilled hobbyist, I’m no chemist. I am using salinity salt mix. I do water changes every 2 weeks 40g.

Other parameters:

Nitrate 1
Phosphate .08 - .04 (running gfo in reactor)
Ammonia 0
Salitiy 1.025

Thoughts? The 2 part I’ve been using is the BRS 2 part system.

saltyfilmfolks · Dec 25, 2017

What two part product are you using ?

aileen · Dec 25, 2017

BRS

https://www.bulkreefsupply.com/brs-2-part-calcium-alkalinity-total-package-bulk.html

aileen · Dec 25, 2017

FYI, I do realize that generally speaking alk of 7 and calc of 420 isn’t in a range of concern, but I’m trying to improve coral growth and calcification by artificially raising alk and calcium to a bit on the higher end. I’m thinking by keeping the alk above 8 maybe near 9 and calcium near 450 I can accomplish that goal in sps growth in conjunction with keeping nitrates around 1 and phos around .04 or so. Maybe I’m wrong?

saltyfilmfolks · Dec 25, 2017

You’ve used the calculator at brs I assume?

aileen · Dec 25, 2017

Oh ya, I’ve used it. But I will admit I broke up the doses the first two days for fear of overdosing. The first time I measured it before dosing it called for nearly 300 ml of alk and calcium so I broke it up into two days.

Randy Holmes-Farley · Dec 26, 2017

100 mL in a 250 gallon system is only 0.6 dKH per day. That is not a large amount, even on top of limewater use.

aileen · Dec 26, 2017

Thank you Randy! Any thoughts on whether my efforts to keep alk and calcium at 8 and 450 are worth it or not? Or, just accept 6.5 and 420?

Randy Holmes-Farley · Dec 26, 2017

aileen said:
Thank you Randy! Any thoughts on whether my efforts to keep alk and calcium at 8 and 450 are worth it or not? Or, just accept 6.5 and 420?

It would be trivial to raise the calcium by 30 ppm if you want, but I doubt it is of any benefit. Just make a one time correction dose of jsut the calcium part.

To keep alk higher will likely require more every day (not just a one time correction), but likely would give faster SPS growth.

maybe try 150 mL per day of each part and see what that does for you.

remember if you measure just before dosing, that's the minimum, and the levels (especially alk) were higher right after dosing.