calcium / alk uptake

TD13 · Jan 18, 2016

I'm using Fritz Calcium in a 5:1 solution so that 5 ml = 1 gram of powder dissolved. The packaging states that 1 gram = 10 ppm. I'm also dosing Soda Ash at a 2 cups/gallon mix. My apex is doing all the heavy lifting for me with BRS 1.1 ml dosing pumps. I am dosing BOTH solutions at 68 ml/day. I know all tanks are different, but I'm really getting into dosing. If my math is right, my coral are taking up 136 ppm / day of calcium (600ml / 120g solution). Does anyone know how to figure the uptake of kH at that solution? And does this sound about normal for a healthy tank? Here are my params...
no3 - 5-10
mag 1390-1410
kH - 12
Calc - 450-460
average temp 78.6
SG 1.026

I have an sps heavy reef with a bunch of frags, everyone looks happy and healthy.

redfishbluefish · Jan 18, 2016

Your calcium solution looks a bit high!

I had to look up Fritz and found that it is the anhydrous form of calcium chloride. You are already using Randy's recipe for alkalinity, why not just use his recipe for calcium. That would be two cups of anhydrous calcium chloride per one gallon total volume. HERE's his recipe.

Randy Holmes-Farley · Jan 18, 2016

you can use calculators here to get doses or uptake in dKH or ppm per day once you know the dose you are using, including the Fritz product by entering anhydrous calcium chloride.

http://reef.diesyst.com/chemcalc/chem_calc3.html

The typically ratio is about 18-20 ppm calcium for each 1 meq/L (2.8 dKH) of alkalinity

TD13 · Jan 27, 2016

@Randy Holmes-Farley which of the choices for Alk is the BRS Soda ash? Also, is there an "Uptake" calculator anywhere?

Randy Holmes-Farley · Jan 27, 2016

Soda ash is sodium carbonate, so use that entry.

I'm not sure what you mean by an uptake calculator. Can you explain what you want from it?

TD13 · Jan 27, 2016

Randy Holmes-Farley said:
Soda ash is sodium carbonate, so use that entry.

I'm not sure what you mean by an uptake calculator. Can you explain what you want from it?

I'm struggling to figure out how much of each (Calc/Alk) are being taken up by the inhabitants of my tank. I'm constantly adding them and then tweaking the dosage. Sometimes it ends up to be too much, sometimes not enough. If I just turn all dosing off and test today, wait 2 days and /2 will this be accurate enough to determine uptake?

Randy Holmes-Farley · Jan 27, 2016

TD13 said:
I'm struggling to figure out how much of each (Calc/Alk) are being taken up by the inhabitants of my tank. I'm constantly adding them and then tweaking the dosage. Sometimes it ends up to be too much, sometimes not enough. If I just turn all dosing off and test today, wait 2 days and /2 will this be accurate enough to determine uptake?

OK, that's beauty of a two part: using a fixed ratio keeps reefers off the roller coaster ride of parameters. So using the fixed dose of each, maintain the alkalinity where you want it, and calcium will follow along and you can very slowly tweak it up or down over time if needed.

You can obviously still do it with independent additives, but it takes a lot more calcium measurements and patience.

The tank should be taking up about 18-20 ppm of calcium and perhaps 0.1 to 2 ppm magnesium for each 1 meq/l (2.8 dKH) of alkalinity.

So if you dose in approximately that proportion, things may be more stable than if you dose completely independently.

Can you describe what is in your tank, or show a picture, to help gauge a starting alk dose?

TD13 · Jan 27, 2016

Sure @Randy Holmes-Farley . 28 Gallon Nano cube. Its SPS dominant, as you can see. I'm mixing my Alk at 2 cups / gallon using BRS Soda Ash. As of NOW I have Anhydrous Calcium Chloride at 5:1 ratio. So I'm going to make a new Batch using your recipe at 2 cups / gallon and run it instead. My ALK 24 hrs ago was 10.22 and now 10.36, im dosing 75 ml/day, so that seems pretty stable.

Randy Holmes-Farley · Jan 27, 2016

hard to tell from the picture, but is the rock covered in coralline and is it growing? Coralline alone can use 2 dKH per day.

TD13 · Jan 27, 2016

There is some, and it is growing a bit. I have seen really good growth from quite a few of my cora. There's a purple stylo in there that has more than doubled in just a month or so. The tank will be a year old ~ Feb 16. I don't mind keeping the Kh 10-11 because I have nutrients to support the accelerated growth without burning tips.

Randy Holmes-Farley · Jan 27, 2016

Do you know how much alk you are dosing in dKH now?

If not, I'd probably try dosing 1.5 dKH of alkalinity per day, with a proportional amount of calcium, and watch it for a few days. Then if the alk is rising, drop back, and if falling, increase it. It is easier, IMO, to make trial and error changes than to determine alk dosing by watching it fall when not dosing.

There are a couple of reasons for that, one of which is the fact that the higher the alk the more demand there is for calcium and alkalinity. So from 11 to 10 dKH might take one day while 7 to 6 dKH may take several days. Also, higher pH when dosing also leads to higher demand.

TD13 · Jan 27, 2016

What ever 75 mL of your recipe of 2 cups soda ash / 1 gallon RO is...

Randy Holmes-Farley · Jan 27, 2016

What size is the tank? The calculator can show the amount of alk that is each day in dKH.

TD13 · Jan 27, 2016

It's a 28 gallon nano with probably 25 gallons of water after displacement. Assuming the formula is 2 cups/ gallon... this is what I put into the "calculator". Not sure I'm using the correct one.

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TD13 · Jan 27, 2016

If their formula is 2 cups/gallon I'm using 10.36(measured) - 8.86 (amount shown as needing 75mL dose) =1.5 dkH / day

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TD13 · Jan 27, 2016

If their formula is 2 cups/gallon I'm using 10.36(measured) - 8.86 (amount shown as needing 75mL dose) =1.5 dkH / day

TD13 · Jan 27, 2016

If their formula is for 2 cups/gallon 10.36(measured in tank) - 8.86 (dkH needing 75mL to meet measured amount) = 1.5 dkH / day

Randy Holmes-Farley · Jan 27, 2016

You need to fiddle with the desired alk part until it gets to 65 mL per day.

And since you are measuring liquid solution and not solid powder, you need to use Randy's recipe 1 (BRS uses my recipe #1).

Doing that, I get 3.6 dKH per day. That could be correct for your tank, if the alk is stable when dosing that amount. But it seems a little high for what I see, and you might try dosing 50 mL per day for a few days and see what happens to the alkalinity.