Two part dosing

BlueDevil · Jan 3, 2017

I have found in recent weeks that my Ca and Alk numbers have been going out of whack even though I dose daily, do weekly water changes followed by checking the levels on each. Any deviation is corrected via manual dosing.

Lately I have seen my Alk drop close to 1.2 dkh over the course of a week while my Ca has remained relatively stable. So I did some reading online and found these articles, one by Randy talking about the chemical 'mirage' that I might be experiencing. I am currently dosing unequal amounts of Alk vs Ca with the belief that I needed more of it. Turns out from my reading, I just need to increase the dosage of each of the two parts.

So, I thought I might check to see how some of you local folks who use two part are dosing your tanks. Equal amount or unequal? What has been the stability of your Alk and Ca?

@cee @seased - your thoughts on this?

Here are the two articles that I found...

http://www.reefkeeping.com/issues/2004-12/rhf/

https://joejaworski.wordpress.com/2014/05/19/the-right-way-to-use-2-part-additives/

Saltmix · Jan 3, 2017

Dos equal parts of cal and alk and keep mag in check. And don't dos at same time like 1/2 hr apart and better to dose in small amounts I dose my tank 2 mm every hr after lights are out /total of 16 mm of each alk and cal and keep testing to get your levels were you need to be better to start out in small amounts /so not to over dose

Joshua Hurst · Jan 3, 2017

I over doesed on calc and it almost killed my birdsnest. It read 520 at one point!?!

bubbaque · Jan 3, 2017

I could never wrap my head around having to dose equal parts of two-part. Even is calcium is at 500 and alk at 7.5 and want to raise it to 8.5 dkh, your suppose to dose more alk and calcium and some how calcium will come down and balance out.

BlueDevil · Jan 3, 2017

bubbaque said:
I could never wrap my head around having to dose equal parts of two-part. Even is calcium is at 500 and alk at 7.5 and want to raise it to 8.5 dkh, your suppose to dose more alk and calcium and some how calcium will come down and balance out.

That is exactly what is puzzling me too! I'm going to try switching to equal amounts of each with a low dose initially and will test daily to make sure that it doesn't get too out of whack. I guess time will tell!

bubbaque · Jan 3, 2017

Maybe @Randy Holmes-Farley can explain it where we understand it.

cale0721 · Jan 3, 2017

When my tank was fully stocked I was doing equal doses for alk and cal. It took me a few days to get it balanced and dial in my doser.

cee · Jan 3, 2017

There's a lot more calcium available than alkalinity in your water so it should come as no surprise that it takes a lot more calcium to raise the level. Also, my dosing is unequal amounts of sodium carbonate (1/2 cup per gallon) and anhydrous calcium chloride (also 1/2 cup per gallon). However, since I've not calculated the ionic concentration of the relevant ions, I may indeed be dosing EQUAL amounts. Unless you're dosing a equal balanced two-part from a reputable dealer, it is almost impossible to say that the dosing is unequal (unless you mix it up yourself and do the math involved). Most times when I detect alk to be low I also notice that Ca is also low, but alk could be 1 dKh low and Ca only 10-20 ppm.

pH, CO2 in your house, phosphates, size and growth rate of coral, type of coral, Mg, strontium and other things also play a role. It is really quite complicated if you consider all the chemistry involved. My advice? Don't over-think it. Find a solution that works for your tank, tweak it as needed, test often and adjust dosing accordingly.

BlueDevil · Jan 3, 2017

Thanks @cee for your input! I certainly am not trying to chase numbers. I like to keep things as simple as possible so the more hands off I am the better! Its just that my numbers were starting to drift away from each other gradually with no obvious changes that I had made. In fact, my Ca had steadily gone up from 430 to 500 and Alk had gone down from 9.0 to 7.8 during my weekly tests over the past month or so. I kept having to dose Alk but never seemed to get caught up which is what led to my reading up on things. Until yesterday, I was dosing 28ml of Alk and 22 of Ca daily at night staggered by an hour each. I am going to tweak my dosing program a little tonight to dose 25 ml of each and test daily to see where I end up. Mg has held steady at 1350 all the while only until yesterday when it tested at 1400. This weekend I did not have time for a water change so I know it wasn't a wonky batch of water that caused this Mg spike.

I'll report back with my results in a week once I have the daily data.

bubbaque · Jan 3, 2017

How does dosing more calc not increase it further?

BlueDevil · Jan 3, 2017

bubbaque said:
How does dosing more calc not increase it further?

I don't quite understand the science (chemistry) behind the chemical mirage as Randy refers to it, though it is likely what I am experiencing. Here's an interesting video which pretty much mimics what I am going through.

BlueDevil · Jan 3, 2017

So my baseline results from today's test are as follows. I will post an update on Saturday (since Sunday is water change day). That should give me 4 straight days of the new program.

1/3/17:
Mg: 1325 (I think my test from yesterday might have been a human error since it was down to 1280 today, and I dosed to bring it up to 1325)
Alk: 8.4
Ca: 500

bubbaque · Jan 3, 2017

That video was amazing at helping me understand how it works. Thanks for sharing it!

BlueDevil · Jan 3, 2017

bubbaque said:
That video was amazing at helping me understand how it works. Thanks for sharing it!

You're welcome!

Chriscrna · Jan 4, 2017

I use recipe 2 of Randy's 2 part supplement system with BRS CaCl dihydrate and Arm and Hammer. (Detailed here......http://www.reefkeeping.com/issues/2006-02/rhf/)

I generally test Mg weekly and keep it around 1300, only dosing as needed. Ca and alk however are on dosing pumps. I guess my question is, what's the consensus on the best time to dose? Day, night, constantly? I divide my daily total of Ca and alk into 24 equal doses (once an hour).

Thoughts? @cee @seased

BlueDevil · Jan 4, 2017

Chriscrna said:
I use recipe 2 of Randy's 2 part supplement system with BRS CaCl dihydrate and Arm and Hammer. (Detailed here......http://www.reefkeeping.com/issues/2006-02/rhf/)

I generally test Mg weekly and keep it around 1300, only dosing as needed. Ca and alk however are on dosing pumps. I guess my question is, what's the consensus on the best time to dose? Day, night, constantly? I divide my daily total of Ca and alk into 24 equal doses (once an hour).

Thoughts? @cee @seased

In your case, since you don't have any pH issues (either low or high) I think dosing on a 24-hr cycle would actually provide more stability to the parameters. I'm sure you know that the Alk and Ca will need to be staggered a little to avoid precipitation.

This is just my two cents worth. I'll let the experts chime in

Chriscrna · Jan 4, 2017

BlueDevil said:
In your case, since you don't have any pH issues (either low or high) I think dosing on a 24-hr cycle would actually provide more stability to the parameters. I'm sure you know that the Alk and Ca will need to be staggered a little to avoid precipitation.

This is just my two cents worth. I'll let the experts chime in

On a 10 minute stagger.

seased · Jan 6, 2017

I also use Randy's 2 part recipe. I use a litermeter to dose - it alternates between alk and calcium every 10 mins - so mine is dosed constantly. I have found over the years that I need to use slightly more alk than calcium. I test it each week or so to make sure it's not getting out of sync. Also, I dose my 2 part with my make up water - one bucket with alk/makeup water and the other bucket with calcium/makeup water.