2 part dosing question

tcoyle · Jul 8, 2015

This might be a long winded question but here it goes…

So I have been dosing 2 part for the past few months using only 1 BRS 1.1ml doser for ALK and manually dosing Calcium as needed. For ALK I have been using Baking Soda, as I am also using kalkwasser in my ATO. I have my doser being controlled by my apex and dosing around 55ml per day starting at 11am and ending at 4pm. ALK has been fairly stable around 8dkh and Calcium around 415-425.

This week I decided to switch to the BRS Soda Ash as my ph has been dropping below 8 at night, even with the KALK. So I set my doser to dose from 9pm - 5am. So far this week my ALK has been dropping from 7dkh - 7.5dkh.

I have been testing my parameters at around 5pm. So when I was dosing the baking soda, I was testing soon after my daily dosing was done. Now when I test for ALK, my doser has not even started yet.

The question I have is this, Should I change when I test to get a more accurate reading, or keep testing at 5pm? Is there a better way to keep the ALK more stable throughout the whole day or is this just the normal consumption rate?

I am adding another doser today for Calcium to dose daily to keep things more automated. I have planned to run that doser from like 11am-4pm to dose an equal amount of calcium.

I am trying to get my ALK stable at around 8dkh again and I have been slowly dosing around 4o ml more per day in addition to 60ml from my doser.

Thanks for the help.

redfishbluefish · Jul 8, 2015

First off, I believe the differences you are seeing are from the differences in when you are now testing. You obviously have some high consumption occurring, so the longer you wait after dosing, the lower your numbers would be. Try to test at the same interval you originally tested at.

I am also curious about the concentrations of your solutions and volumes added. The solubility of baking soda is considerably less than soda ash. If you're following Randy's recipes, the baking soda solution is half the concentration of the soda ash solution. You'd now dose approximately half the volume of what you were dosing with baking soda. Are you doing this or did you make an equivalent solution of soda ash by using half the recipe amount?

Randy Holmes-Farley · Jul 8, 2015

I agree, the alk will be highest when you finish dosing and lowest before you start. So testing timing will impact the measurement unless you spread the dose out through more of the day.

As Red Fish asked...How did you decide how much sodium carbonate (soda ash) to dose?

tcoyle · Jul 8, 2015

I used the directions on the BRS container. 2.5 cups per gallon or RODI. On Monday I reduced my dosage down to 40ml to make sure it was not more concetrated then the baking soda as I read that you would use less of the sodium carbonate then the sodium bicarbonate. When I was using sodium bicarbonate I was mixing up 2 cups per 1 gallon.

So what is a good time to test both ALK and Calcium to get the average level when your dosing around the clock like this?

Thanks guys!

redfishbluefish · Jul 8, 2015

I say this with ignorance because I do not use BRS chemicals, but I was under the impression their recipes were taken from Randy's recipes HERE.

If that is the case, the soda ash solution should be 2 cups per gallon and the baking soda 1 1/8 cups per gallon. Without cracking the good book, I'd be shocked and surprised if you could get 2 cups of baking soda to dissolve in a gallon of water.

Randy Holmes-Farley · Jul 8, 2015

I'm surprised you could get 2 cups of unbaked sodium bicarbonate (baking soda) to dissolve in a gallon. When I designed the DIY two part, I used 1 and 1/8 cups baking soda per gallon because it is less soluble than sodium carbonate, and even then a lot of folks have problems getting it to dissolve.

If you are dosing through the day and night evenly, any time to measure is fine. If you dose from 11-4, I'd measure at least once just before and after dosing to see how much it changes.

Randy Holmes-Farley · Jul 8, 2015

redfishbluefish said:
I say this with ignorance because I do not use BRS chemicals, but I was under the impression their recipes were taken from Randy's recipes HERE.

If that is the case, the soda ash solution should be 2 cups per gallon and the baking soda 1 1/8 cups per gallon. Without cracking the good book, I'd be shocked and surprised if you could get 2 cups of baking soda to dissolve in a gallon of water.

You type faster than me, apparently.

redfishbluefish · Jul 8, 2015

Randy Holmes-Farley said:
You type faster than me, apparently.

Sorry, I'll type slower next time.

But also please correct me if I'm wrong about BRS recipes.....they are yours, aren't they?

tcoyle · Jul 8, 2015

Hmm.. Well sorry I was wrong on the Soda Ash, I am only using 2 cups, not 2.5… baking soda was at 2 cups per 1 gallon, I'm almost positive. Which might be why my amount dosing is off as I was dosing a higher concentration then I currently am.

So how does this sound…. Dose ALK (soda ash) from 9pm - 5 am test at 6am daily. Dose Calcium from 11pm - 4pm test daily at 5pm to get my readings?

Is there a level that is too much of a swing for the ALK from the time its not dosed to the end of dosing that I should be concerned about?

Thanks so much for all your input. Some day I will figure out this 2part dosing and hopefully with having both ALK and Calcium on a doser I can keep things more stable.

Randy Holmes-Farley · Jul 8, 2015

The concerns about the alk swing depend on what sort of corals you keep, and possibly also whether you keep nutrients especially low.

1 dKH should be OK, and dosing at night only will keep the pH drop from being as large.

Is there a reason you don't want to expand the alk dosing to most of the 24 h? Calcium need not be dosed especially slowly or evenly.

tcoyle · Jul 8, 2015

My tank is becoming more SPS heavy, with mostly acro frags and moni caps.

Nutrients are low, phosphate 0 and nitrate 0. But not carbon dosing… I guess just a bigger skimmer and not a huge bio load.. 5 small fish in a 65 gallon with a 30l sump. I calculate my total water volume around 75 gallons or so.

I was under the impression, maybe wrongly, that you did not want the calcium and Alk to be dosed at the same time. If its not a problem I could easily dose the ALK in a 24 hour period and the Calcium in a much quicker shorter period of time. What do you think that should look like?

Also should I stop doing KALK if I am dosing 2part now or keep the KALK… To me it seems that the KALK is not adding a lot as my evaporation is only 5 gallons per 6 to 7 days. I am using 6 teaspoons per 5 gallons.

Randy Holmes-Farley · Jul 8, 2015

[QUOTE="tcoyle, post: 2357019, member: 33859"

I was under the impression, maybe wrongly, that you did not want the calcium and Alk to be dosed at the same time. If its not a problem I could easily dose the ALK in a 24 hour period and the Calcium in a much quicker shorter period of time. What do you think that should look like?
.[/QUOTE]

While alk might change 30% in 24 h of no dosing, calcium changes only very slightly (say, 4%).

For example, if you start at 10 dKH and calcium 450 ppm, in 24 h you might be at 7 dKH and 430 ppm calcium.

So you could dose all of the calcium in 30 minutes and dose the alkalinity for the remaining 23.5 hours. Or some such plan.

You could also dose them at the same time if you dose in physically separated locations (in a big enough system).

I'd keep using the limewater (kalkwasser) to help boost pH, but it is also OK to stop it.

tcoyle · Jul 8, 2015

Thanks so much Randy! I appreciate your help… Got the new calcium doser all hooked up.
My Alk is now dosed from 1am - 11pm
Calcium 11:10 - 1am

Came home and tested tonight and my Alk was at 7.7, so I am headed in the right direction.