Huge Calcium Spike???

Brandon McHenry · Jun 17, 2020

Hi all! So I had something strange happen today and I need some more brains. Yesterday my parameters were:

Ca-430 (salifert)
Alk-6.6 (Hanna)
Mg-1350 (salifert)
Salinity-36 ppt (freshly calibrated refractometer)

This morning I decided to take a few cups of saltwater out and allow my ATO to replenish in an attempt to bring my salinity down to 35ppt. This evening I tested my tank and my calcium is up to 500pppm! However the salinity has come down to 35ppt. I have no idea how this is possible unless I had a doser malfunction. I tested my RODI water and it is 0tds and 0ppm calcium so I don’t think it was that. If @Randy Holmes-Farley or any of the other reef chemistry gurus want to take a crack at this and help me out I’d really appreciate it!

Rybren · Jun 17, 2020

I'd see two possibilities:

- test error (either on the 430 readings or the 500 reading)
- you somehow added a lot of calcium to the tank

Brandon McHenry · Jun 17, 2020

Rybren said:
I'd see two possibilities:

- test error (either on the 430 readings or the 500 reading)
- you somehow added a lot of calcium to the tank

Agreed it doesn’t make sense. The test kit is brand new, and I’ve been using it for the last few weeks all hovering at around 430-440. Then today three tests in a row all read 500. I’ve never had a doser malfunction and dump a bunch of additive into the tank before. I don’t even know if that’s a possibility or not but I don’t see another explanation.

Rybren · Jun 17, 2020

Doser malfunctions have happened before. Sometimes they get stuck on and sometimes the calibration goes off and you get more or less than expected with each dose. It's worth checking the doser.

Brandon McHenry · Jun 17, 2020

Rybren said:
Doser malfunctions have happened before. Sometimes they get stuck on and sometimes the calibration goes off and you get more or less than expected with each dose. It's worth checking the doser.

Based on the math the doser would’ve had to add ~175 mL over the course of the day to jump 70ppm with ESV B-ionic. My doser is only set to 23mL per day. How can I check if the doser got stuck on?

X-37B · Jun 17, 2020

Brandon McHenry said:
Based on the math the doser would’ve had to add ~175 mL over the course of the day to jump 70ppm with ESV B-ionic. My doser is only set to 23mL per day. How can I check if the doser got stuck on?

Dose into a seperate container for a few days and dose the tank by hand if needed.
Its about the only way to tell.

Brandon McHenry · Jun 17, 2020

90's reefer said:
Dose into a seperate container for a few days and dose the tank by hand if needed.
Its about the only way to tell.

When I retest tomorrow I can pull the dosing tube out and see about putting it into a container to watch what it’s dosing. That sounds like a good idea.

Rybren · Jun 18, 2020

Brandon McHenry said:
When I retest tomorrow I can pull the dosing tube out and see about putting it into a container to watch what it’s dosing. That sounds like a good idea.

You should do this when you first set up the doser anyway, otherwise you don't know how much you are dosing. Relying on the factory settings to be accurate is just asking for trouble (IMHO). Periodic checking of the doser is also prudent because they can change over time.

Brandon McHenry · Jun 19, 2020

So I did a decent (30-40%) water change with Tropic Marin Pro and I removed the calcium tube. I will let the calcium fall naturally and I will assess how much the doser is dosing on that channel.