Homemade Two Part Question

Calcium and Alk solution are added in equal parts since they're utilized by corals in equal parts. Bulk Reef Supply's solutions are balanced right out of the box. 1/4 cup of calcium solution contains as much calcium as 1/4 cu. of alk solution contains alk.

I've started to make my own solutions. I used Randy Holmes Farley's recipes--using Prestone Driveway Heat (calcium chloride) 400g. and enough water to make a gallon for the calcium, and baked baking soda and borax (4:1) for alk solution. That comes out to 594g of baked baking soda and 150g of Borax.

I want to confirm that my alk and calcium solutions are equal in concentration of their respective components.

Is this as simple as a ppm thing? For example if I dilute each solution to make them compatible with test kits--should the ppm of ca equal the ppm of alk?

 

i take it that the answer is no? actually, im almost positive that they arent equal... i believe you will use approx 3x more alk than ca unless randy already corrected for the molarity of the alk/ca

Im not chemist but i think to do this properly, you will have to take the same amount of ca and alk and dissolve them in the same amount of water and then measure molarity... since we cant measure that then it seems like a dead end for us normal people.

One other method i can think of, but am not sure of, is to play guess and check with one of those online ca and alk calculators... just specify that you are using randy's mix and then put in your ppm and then set it to how high you want to go and see how many g you must add to raise it, then do the same for the other part using the same numbers and see if the g are the same. it might work, but im not sure?

 

That makes sense, Trent. Thanks.

I considered taking some tank water with balanced cal and alk, and adding the same amount of my solution to each, and then measuring the resultant values--but that would be inexact due to degree of error in measurement. I like your idea of the calculator a lot better.

I wonder if anyone else has thoughts on this.

 

I followed the instructions and have been dosing with home made chemicals for about 6 months now with no worries, I just add equal parts Ca in the daytime and Alk at night, I drip these slowly in my top off water. About ever two weeks Ill do water tests and if one has drifted slightly Ill skip a day or two on either the Ca or Alk whichever is higher until they are balanced again

 

Thanks, bluetang08. That was the final way to establish if they're balanced. Time and testing.

I do appreciate everyone's input. For my own knowledge, I'm really after a chemical way to confirm that two given quantities of these liquids will contribute equal amounts of their respective ions.

 

I like reading smart posts by smart folks... any time a thread has intelligent discussion on molarity and I have to remember my college chemistry, I know I stand amongst folks smarter than I....

A question for you smart people.... I use an Aqua-medic two-part doser. You can only set it to a frequency.... add so many ml every so many minutes..... how do you control yours to separate Ca and Alk???? I have mine set to add a touch of Ca every 40 minutes or so and then Alk once every few hours. Should I be doing that differently???

Thanks
M

 

What I'm trying to achieve is for the pH to be uniform over 24 hours. Since pH will drop at night and rise during the day, and since addition of alk causes pH to rise--we can use that to our advantage.

My dosing pumps administer 1/4 cup of each solution overnight. It's a 12 hour period, and 1/4 cu (60 ml) is about 5 ml. each hour. The calcium and alkalinity solutions are offset by 30 min's so they're not dripped at the same time. When my halides go off at 7, the calcium comes on first (calcium addition doesn't cause pH to change) for a few min's to dose 5 ml. Then, at 30 min's past the hour, alk is dosed--same amount. The staggering of the two prevents precipitation that might occur if dosed concurrently. Alk comes after calcium only because the pH decline resulting from lights out doesn't manifest itself until about 30 min's after no light. If alk came immediately after lights out, the pH would spike before beginning its decline.

So when I view the graph of my pH, it rises slowly starting at 11am when halides come on, and begins to decline after 8pm. Instead of a smooth line of decline, it's interrupted by short spikes caused by the alk dosing.

I'm aiming for the most gradual decline possible. The pH will go down--but dosing can mitigate the swings a bit.


EDIT:

Your question brings up the reason why I asked my question at the top of this thread. I'm using the last of my BRS two part solution, and I'll be running out of calcium when I have about 50% of my Alk solution remaining. Now that I'm making my own (see below), I'm not confident that the solutions are of the same molarity.

 

I hear ya.... what system are you using to dose Ca/Alk???

 

I'm not sure if you're referring to the pumps, setup or the liquids. I use BRS's peristaltic doing pumps run off an Apex controller. For the solutions, I make them myself with Randy Holmes Farley's recipes. Alk solution is about 600g of baked baking soda, and calcium is 400g. of Prestone's Driveway Heat. Each dry material is mixed with enough RO/DI water to make 1 gallon. BRS is fantastic, but by using the Prestone and Arm And Hammer, I save a bit. The Prestone will make about 10 gallons of solution and was $9.75 online. The Arm And Hammer, well, you know how much that stuff costs.

 

I was referring to the BRS's peristaltic doing pumps run off an Apex controller.

You can't offset like that with Aquamedic. I like what you are trying to do. I'll have to think through the 'best' I can do with what I have.

Today though, I am still doing battle getting my skimmer working consistently again ...... it has always been 'sensitive' but once I moved it to this new tank, I can't seem to get it working.

M