Calcium Dose seems unreasonable

[Sloopy]

I have a system with about 350 gal (150 gal display) at a salinity of 36. I have a few small (struggling) corals, and yet even dosing 650 ml of Kh (Soda Ash) and Ca (Calcium Chloride) daily (BRS dry mix that I'm making according to the instructions, hourly small dose via a dosing pump) my Kh hovers a little high, but my Ca can get below 200.

I get a not insignificant buildup of a tan solid on my tank walls and equipment (have to clean the pumps in vinegar every 2-3 weeks).

I'd really appreciate help understanding what I'm doing wrong. Mg levels around 1240.

 

[Randy Holmes-Farley]

I have a system with about 350 gal (150 gal display) at a salinity of 36. I have a few small (struggling) corals, and yet even dosing 650 ml of Kh (Soda Ash) and Ca (Calcium Chloride) daily (BRS dry mix that I'm making according to the instructions, hourly small dose via a dosing pump) my Kh hovers a little high, but my Ca can get below 200.

I get a not insignificant buildup of a tan solid on my tank walls and equipment (have to clean the pumps in vinegar every 2-3 weeks).

I'd really appreciate help understanding what I'm doing wrong. Mg levels around 1240.

Sounds like a possible test problem. There no way that seawater can get down to 200 ppm calcium without adding massively more alk than calcium. It would take 30 dKH of alk to drop calcium by 200 ppm.

Have you used that kit on some new salt water?

How high is the alk?
650 mL in 350 gallons is 2.6 dKH per day and 18 ppm calcium.

That's not super high, but you may have ongoing precipitation of calcium carbonate.

If the 200 ppm value is correct, you need to add several liters of just the calcium part. This calculator and the entry for Randy's recipe 1 will help:

Reef Chemistry Calculator

To reduce precipitation, there are a bunch of steps, but first we need to know the alk. Letting it fall to 7 dKH with no alk dosing is the first step.

 

[Sloopy]

Sounds like a possible test problem. There no way that seawater can get down to 200 ppm calcium without adding massively more alk than calcium. It would take 30 dKH of alk to drop calcium by 200 ppm.

Have you used that kit on some new salt water?

How high is the alk?
650 mL in 350 gallons is 2.6 dKH per day and 18 ppm calcium.

That's not super high, but you may have ongoing precipitation of calcium carbonate.

If the 200 ppm value is correct, you need to add several liters of just the calcium part. This calculator and the entry for Randy's recipe 1 will help:

Reef Chemistry Calculator

To reduce precipitation, there are a bunch of steps, but first we need to know the alk. Letting it fall to 7 dKH with no alk dosing is the first step.

I'm extremely grateful for the response. I was starting to feel a little hopeless.

I'll order a new test kit in case that's the issue. (I've been using the Red Sea foundation pro kits, I'm open to change if recommended), and also test the salt water I'm adding during water changes.

I can simply pause the Alk dosing until I get to 7.0

Thank you for your help.

 

[JAC-]

I completely agree with Randy, but the redsea kits are usually pretty good. I'm a Hanna fan, but it's a big upfront investment. Well worth it in my opinion though. Definitely for the alk.

Are your kits in date and are you properly washing out the sample containers with RO water?

Have you watched the instructional videos?




I'd also check this out top 21 testing mistakes,



Best of luck my friend,

 

[Sloopy]

I appreciate the help so far. I'm careful to rinse out test vials after every test, but just to be sure, I cleaned them all again.

On Sunday I paused my Alk dosing (leaving Ca on), and performed a 10% water change with Reef Crystals at 35ppt.

Readings tonight have Kh at 8.4 and Ca at 280 ppm.

New test kits arrive later this week.

 

[Sloopy]

Sounds like a possible test problem. There no way that seawater can get down to 200 ppm calcium without adding massively more alk than calcium. It would take 30 dKH of alk to drop calcium by 200 ppm.

Have you used that kit on some new salt water?

How high is the alk?
650 mL in 350 gallons is 2.6 dKH per day and 18 ppm calcium.

That's not super high, but you may have ongoing precipitation of calcium carbonate.

If the 200 ppm value is correct, you need to add several liters of just the calcium part. This calculator and the entry for Randy's recipe 1 will help:

Reef Chemistry Calculator

To reduce precipitation, there are a bunch of steps, but first we need to know the alk. Letting it fall to 7 dKH with no alk dosing is the first step.

I've been letting the normal CA dosing go, and adding an additional 83g of Calcium Chloride (in 20 oz of water) daily. As of tonight, that has Kh at 7.15 and Ca at 310.

 

[Randy Holmes-Farley]

I've been letting the normal CA dosing go, and adding an additional 83g of Calcium Chloride (in 20 oz of water) daily. As of tonight, that has Kh at 7.15 and Ca at 310.

OK, sounds like a fine approach.