Dosing new saltwater

balix · Apr 5, 2019

Hi guys,

I’ve recently switched over to using an apex doser for small daily water changes.

Is it possible to dose my container of new saltwater to catch up with what my tank is consuming on alk and calcium? For instance Like raising calcium to 600-700 and Alk to 12-13. Any precipitation of concern? Currently using blue bucket of Red Sea.

I have a 70gallon tank. Removing and adding 3L of old and new saltwater daily.

WWIII · Apr 5, 2019

I think I would rather dose directly to the tank for those kinds of adjustments. Make the manual corrections over a few days/week. I would just keep the auto waterchanges going with water similar to where you want your tank to run. I would think it would be technically possible to do what you're suggesting, but making adjustments directly to the tank will probably be easier to control. Maybe someone else has tried what you're suggesting though?

ryeguyy84 · Apr 5, 2019

In theory yes, that's kinda how a calcium reactor works.

You would have to do a lot of experiments to get it right and find the levels where Cal/alk don't prercipitate out

Dkeller_nc · Apr 5, 2019

I suspect you'd have major problems keeping the new salt water in your change reservoir at a stable alkalinity and calcium level if they were adjusted to that high of a level. Bulk Reef Supply did a video on different salt water mixes and their stability as far as alk and Ca were concerned over a 3 week storage period. Most of the mixes held fairly steady, but the Red Sea Coral Pro salt, with sharply higher levels of alk and Ca, dropped significantly over that period. Here's the video.

Randy Holmes-Farley · Apr 6, 2019

The numbers you quote are off (much less calcium, more alk), and this generally won't work for most tanks as the needed alk would be too high unless the demand is very low.

Suppose you need 2 dKH per day of alk, and you change 1% of the tank water daily.

Then the new water needs to have alk that is 200 dKH higher than the tank water.

here's the math for 7 dKH tank water):

0.99 (7 dKH) + 0.01 (200 dKH) = 6.93 dKH + 2.00 dKH = 8.93 dKH (which is a bit less than 2 dKH added daily).