Randy 2 part question

[clownsrcool]

Randy,

I live in Tx and don't really know where I can locate what is needed for the calcium portion of your DIY mix. I figured I can at least save some money and at least make the Alk portion on my own.

I have some questions for you regarding the Alk portion. I was going to use the recipe #1 and from the looks of it the alk level of that solution will be about 2x higher than the level would be of recipe #2. Does that mean you need to dose half as much?

I currently use the BRS mix and am unsure how to calculate how their mixed solution will compare with yours. What i mean by that is if i dose 60ml now of their mixture what will i need to dose for yours? Are they an equal comparison?

Same thing goes for the calcium mixture. Lets say you tell me i need to dose 50% more of your solution than what i am doing with the BRS mixture. Since i will be using the BRS mixture for CA and yours for ALK then my dosing amounts for each would be different then right?

 

[Randy Holmes-Farley]

BRS uses my DIY recipe, so it is the same as mine using baked baking soda. They just have already baked the baking soda (by buying sodium carbonate). Yes, my two recipes differ by a factor of 2 as the unbaked baking soda is less soluble in water.

If you do not bake the baking soda, and do not want to dilute the calcium from what you use now, then yes, dose half as much of the calcium solution as the alk solution. If you make it half as strong, then dose the same amount as the alk part.

 

[beaslbob]

BRS is a fine source.

For calcium chloride you might try asking for calcium chloride at you local redimix concrete places. It is used to speed hardening of cement at lower temperatures.

IME the really hard part to find is the magnesium chloride. I found a source locally at an industrial chemical supplier.

my .02

 

[clownsrcool]

Thanks for the tip on the calcium chloride. Luckily I have never had to dose MG. My water changes seem to take care of that on their own.

 

[Randy Holmes-Farley]

Thanks for the tip on the calcium chloride. Luckily I have never had to dose MG. My water changes seem to take care of that on their own.

Perhaps, but it is still better to dose it. The two part (both mine and all commercial ones) are designed so that if you dose as directed to maintain alkalinity, it keeps a lot of things where they should be: calcium, alkalinity, magnesium, chloride, sulfate, potassium (if include din the mix), etc. That is the beauty of a two part oven simple independent additions of calcium and alkalinity when needed.

I know people often neglect the magnesium part, but it is used not just for magnesium (it is the only source of sulfate in the DIY system), and dosing it as directed won't cause magnesium to rise, only stay where it is.

 

[clownsrcool]

My mag level has been slowly creeping upward since the tank has been set up and I haven't dosed anything for it in that time. I have worried that if I did dose anything for it it would sky rocket. So you are saying that dosing won't increase that value? That doesn't make sense to me.

 

[Randy Holmes-Farley]

My mag level has been slowly creeping upward since the tank has been set up and I haven't dosed anything for it in that time. I have worried that if I did dose anything for it it would sky rocket. So you are saying that dosing won't increase that value? That doesn't make sense to me.

Well, I'm happy to explain in detail why it doesn't raise magnesium when dosed exactly as I recommend. I also show it mathematically in my articles. FWIW, most commercial two parts include it in the calcium portion, so people do not know it is even there, but it is. In my DIY is just seems more apparent.

There are two sinks for magnesium in a reef tank using a two part that the two part is supposed to exactly account for and offset.

One is that when calcium carbonate is precipitated by corals or coralline algae for their skeletons, or in abiotic precipitation on pumps and heaters, a certain known amount of magnesium gets into the crystal in place of calcium, so magnesium declines. The biological removal into skeletons varies a bit with the coral type, so the value in a two part is usually is an average estimate. FWIW, this depletion of magnesium is VERY slow, typically 0.1 to 2 ppm per day. So it may go unnoticed for a very long time, even when dosing none, and the addition of magneisum to offset it likewise will go unnoticed for a long time even if none were depleting.

Second, all two part additives slowly raise salinity due to the sodium and chloride (and other ions) that are added. When you reduce the salinity back to normal (whatever that value is for you), everything in the tank declines in value, including magnesium. So a well made two part includes just the right amount of magnesium to offset this necessary decline. This type of magnesium depletion is bit more more than twice as much as is incorporated into skeletons. There is no way around this depletion without adding it.

Curious that you say magnesium is creeping up. There's no mechanism for that aside from additions of magnesium, salinity creeping up, or water changes with a salt where the magnesium is higher than the tank level. How much is it rising? it might just be testing error.

 

[clownsrcool]

It used to hover in the 1400s. That was over a period of 5 months. Then I decided to stop testing it for a while since it never seemed to change much. I tested it again 8 months after that and got a reading of 1600. I have never dose an ounce of it. It could be a false result from my test. You just were involved with a thread of mine where my hanna checker was giving me false readings. I see that BRS recommends to dose the entire gallon of MG after you have dosed an entire gallon of both the Alk and CA solution but that seems wrong to me. It seems like if I did that my levels would rise so much they would be out of control.

 

[Randy Holmes-Farley]

I think 1600 ppm magnesium without dosing is probably testing error, although some mixes may have magnesium in the 1500's.

They DO NOT recommend dosing the whole gallon of magnesium at once. I do not advise that either.

When I designed the DIY two part, I had folks make up a gallon of the magnesium mix, and dose only 610 mL (20.6 ounces) of it after each gallon of the other two is finished. NOT a whole gallon. That is also what BRS advises.

They recommend:

http://www.bulkreefsupply.com/instructions/article/Instructions-for-Bulk-Packaged-Materials

"Once the dose is dialed in continue daily dosing until the gallon jugs of Calcium and Alkalinity are finished. At this point it is time to dose 20oz of the Magnesium solution. This can be done entirely in one dose just remember to add slowly to a high flow area of the tank.

It is OK to dose the Magnesium portion in multiple doses instead of one dose at the end. If you opt to do this, just keep to the following ratio: 20oz of Magnesium solution for every 1 gallon of Calcium and Alkalinity. (20oz Magnesium:1 gallon Calcium:1 gallon Alkalinity)"

FWIW, in a 100 gallon tank, that 20 0z magnesium addition will add about 75 ppm of magnesium, after having added about 370 ppm of calcium and 53 dKH of alkalinity. In a tank smaller than 100 gallons, it is certainly fine to spread the magnesium out into as many small additions as you want. If the demand is low for calcium and alkalintiy, the magneisum additions will also be low on a daily equivalent basis. If it takes you three months to use a full gallon of the alk part, then the magnesium dose rate is only 75 ppm/90 days = less than 1 ppm per day.