Unequal Dosing Question

[Randy Holmes-Farley Verified Community Expert]

That's the calculator I recommend.

 

[Cperkins]

I have found a good way to slow down magnesium consumption is to scrape your coralline back a lil bit.

 

[petemichelle]

I've been struggling with this same issue. I've read a lot about it and have had a lot of great comments from others about it, but the numbers I get don't match what I keep hearing. I have a heavy SPS tank and use Instant Ocean Reef Crystals and my Alk dosing is considerably higher (over twice as much per day) than my calcium dosing. I tried matching the two amounts for a few days and my calcium shot way up. I tried dosing less alk and sure enough my values droped way below where I want them. In just a couple of days it was 150ppm vs the 180 ppm I had before. With stability being so important, I was afraid I was going to start killing off corals. I went back to the daily does that keeps each value where I want it. Everything in the tank looks happy and the numbers test properly. I've calibrated my test kits and believe the results I'm seeing.

However, my sandbed is clumping up in some places, and I think the extra alk is going towards that. I dose magnesium by the gallon when I use up a gallon of Alk and it seems to keep the mag value where I want it. I'm not sure what the answer is.

how do you actually dose the magnesium and you say "by the gallon" how much per gallon of alk?

 

[petemichelle]

lets hear from different people please. how much do magnesium do you dose and how do you figure that amount out? i've always wondered.

 

[Damion]

My tank consumes more than twice the amount of Alk than Calcium as well. Funny thing, my Mg kept going up and up while I kept backing down the dose. So I've had to turn off my Mg doser because I've found my Instant Ocean mixing up at 1450 Mg! (1.023) (DOS AWC) A quality problem I suppose.

 

[Randy Holmes-Farley Verified Community Expert]

how do you actually dose the magnesium and you say "by the gallon" how much per gallon of alk?

I give the directions for use of this two part here:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2006-02/rhf/index.php

from it:

This solution is added much less frequently than the other two parts. Each time you finish adding a gallon of both parts of Recipe #1, add 610 mL (2 ½ cups) of this stock solution. You can add it all at once or over time as you choose, depending on the aquarium's size and set up. Add it to a high flow area, preferably a sump. In a very small aquarium, or one without a sump, I suggest adding it slowly.

 

[Randy Holmes-Farley Verified Community Expert]

lets hear from different people please. how much do magnesium do you dose and how do you figure that amount out? i've always wondered.

My recommendation is to add the recommended amount based on the recipe unless you find magnesium is actually getting too high (or is already too low and needs a manual correction).

 

[Damion]

You can go day by day to get started.
Test your Mag, go to the BRS calculator, see how much you need to does to true up. If it is small enough to add at once, then add it manually, Day2 test and true up, Day 3 test and true up, Day4 program your dose to dose the average daily you just did the last 3 days. A Good start.

 

[Garbonzo]

I've run into the same dilemma when it came to dosing two part. It seems I have to set the doser approximately 25-30% higher for alkalinity to keep it up in the 10s and carry my calcium at 440ppm, and at first I was a little worried about long term creep, but 3 months of daily testing indicates there's it's the way to fly.

btw I'm using the BRS two part at 24 points, and Mg is sitting at 1440

 

[Randy Holmes-Farley Verified Community Expert]

Now I'm not sure what to think about any of my dosing.

I've been using the reef calculator at http://reef.diesyst.com/flashcalc/flashcalc.html. According to it, to move calcium from 430 to 550 with recipe 1 would take 7369 ml for 600 gallons.

That's a good calculator. I calculated for Recipe 2, you did for #1. We got the appropriate answers.

(old post I see )

 

[Randy Holmes-Farley Verified Community Expert]

I've run into the same dilemma when it came to dosing two part. It seems I have to set the doser approximately 25-30% higher for alkalinity to keep it up in the 10s and carry my calcium at 440ppm, and at first I was a little worried about long term creep, but 3 months of daily testing indicates there's it's the way to fly.

btw I'm using the BRS two part at 24 points, and Mg is sitting at 1440

Have you measured the output of the dosing pumps to be sure they are the same?

What salt mix are you using for water changes?

 

[Garbonzo]

You know, I haven't compared them. I suppose that's one basic step I skipped, but it makes perfect sense. I use Reef Crystals; however, I do maybe 15% changes a month as it seems my system remains healthier with less.