Dosing 2-part unequally

MartinM · Feb 23, 2022

So, I’ve ran into an issue relatively recently. I’ve been dosing C-balance on my ~1000 liter system at 300ml/day for many months, along with kalkwasser in the top off water. However, recently I noticed the calcium trending down and the alkalinity going too high (I ended up with a CA of 320 and an Alk of 14.1, partly due to a dosing pump failure). I was able to correct the problem by increasing the calcium component to 350ml/day and reducing the alkalinity component to 200ml/day And ceasing the kalkwasser for now (it kept pushing the alk too high).

Now my Calcium is ~390 and alkalinity is ~10DKH (measured daily via Alkatronic/Mastertronic and weekly via Hannah test kits, calcium is slowly climbing back up). Is it ok to modify the amounts being dosed based on parameters and not dose them equally?

(Btw, the 2-part dosing may seem high, but I have 9 clams, 6 of them large (18cm+, up to 30cm+), along with SPS and lots of snails)

rtparty · Feb 23, 2022

Rarely have I ever seen a tank use a true 1:1 ratio with 2 part. They always drift apart at some point like this. Dose to what your tank needs, not what a label says

Arego · Feb 23, 2022

I've never dosed 1:1 that would make my life much easier.

Randy Holmes-Farley · Feb 23, 2022

The primary reasons for not 1:1 (aside from bad product designs, like Seachem Reef Fusion) or two part systems that are literally not intended to be 1:1 (like Red Sea) are water changes, rising or falling or dosing nitrate, or the use of sulfur denitrators.

It's fine to make whatever long term corrections are needed. But IMO, the default should be to dose 1:1 unless calcium is already too high or too low.

Note that kalkwasser is unbalanced toward too much calcium, so long term it will raise calcium.

MartinM · Feb 23, 2022

Thanks Randy! Hopefully I’ll be back to 1:1 soon. C-balance has magnesium and strontium also so I wouldn’t want those to swing either by dosing incorrect ratios. (Mg is 1341 at last measurement).

Randy Holmes-Farley · Feb 23, 2022

MartinM said:
Thanks Randy! Hopefully I’ll be back to 1:1 soon. C-balance has magnesium and strontium also so I wouldn’t want those to swing either by dosing incorrect ratios. (Mg is 1341 at last measurement).

To some extent, the amount of magnesium to incorporate is guesswork because some organisms (especially coralline algae) deposit a lot more magnesium in their calcium carbonate than others.

I show data for a bunch of organisms here in Table 1:

Aquarium Chemistry: Magnesium In Reef Aquaria

This article details the nature of magnesium in seawater, how it is added, measured, and removed from marine aquaria, and how it impacts the maintenance of calcium and alkalinity.

reefs.com