View Full Version : Sodium bicarbonate and soda ash

10/05/2016, 03:59 PM
My calcium reactor needs cleaning and refilling, but I wont be getting to that job for a few more weeks. I still have a hefty supply of soda ash and sodium bicarbonate from when I dosed to maintain alkalinity. For the life of me I cannot remember how I used both. I remember soda ash alone raises alkalinity to intolerable levels. I have the formula for dissolving the dry into a liquid, but I don't remember how I dosed them. Any suggestions?

10/05/2016, 04:01 PM
There are several calculators online that will tell you how much to dose. I think the one at BRS is fairly popular these days. Also check out Randy's DIY 2-part instructions. I don't have the link handy but Google can find it right fast. Should be the first hit if you search for "Randy DIY 2-part"

10/05/2016, 10:06 PM
Soda ash is okay on its own if it's not overdosed. Sodium bicarbonate is a little safer since it doesn't change the pH much.

Here's one calculator:


This article has the DIY 2-part recipes:


10/06/2016, 05:10 AM
Are you mixing the two together making them into a buffer, or just using them separately? If separately, use this calculator (http://reef.diesyst.com/flashcalc/flashcalc.html), fill in the blanks for your system, and select Randy's recipe #1 for the soda ash supplement, or Randy's recipe #2 for the bi-carb supplement. I tried mixing them for a while @ 15% soda ash to 85% bi-carb to mitigate any potential pH issues. Using this buffer I found that using 80% of the recommended dose for Randy's recipe #2 from the linked calculator would get me fairly close to the recommended target. Even dosing them separately may require a little trial and error. Ultimately, I started using plain soda ash, since the bi-carb was difficult to get into a solution, and dosed slowly the soda ash didn't elevate the pH enough to be problematic.

10/06/2016, 01:50 PM
I agree that 85% baking soda and 15% soda ash will be pH neutral, if that's the question. Using baking soda by itself might drop the pH by 0.06 units or so for a short period of time until aeration brings the pH back up.