Water Change

PeaBrain · Mar 10, 2020

Just wondering if it's common to dose fresh salt water with 2-part and Mg to get the levels up to match the DT. I have noticed Reef Crystals falls short of Ca and Mg at 1.024 or 25. I think last time I tested the new water Ca was around 360 or 380.

LovesDogs_CatsRokay · Mar 10, 2020

Yep, I think lots of people do this to avoid swings. I add alk to my water before a water change. I use tropic Marin pro and it intentionally has low alk levels.

Quietman · Mar 11, 2020

Not sure if I consider that something worth doing. 90 gallon with nominal 420 ppm CA and 10% WC with 360 ppm you're only going to have a drop of 6 ppm. Yes that's a change, but not sure it's worth the trouble for a normal 10% weekly water change. Larger changes of course may warrant the effort.

Curious...what kind of changes in Ca/Alk do you see now after a water change? And what volume water change do you normally perform?

PeaBrain · Mar 11, 2020

Quietman said:
Not sure if I consider that something worth doing. 90 gallon with nominal 420 ppm CA and 10% WC with 360 ppm you're only going to have a drop of 6 ppm. Yes that's a change, but not sure it's worth the trouble for a normal 10% weekly water change. Larger changes of course may warrant the effort.

Curious...what kind of changes in Ca/Alk do you see now after a water change? And what volume water change do you normally perform?

I normally do 30% water change, and I think I have revealed a 20-30 ppm drop in CA before. I will have to check my notes. I know it has dropped in the past somewhat.

Quietman · Mar 11, 2020

PeaBrain said:
I normally do 30% water change, and I think I have revealed a 20-30 ppm drop in CA before. I will have to check my notes. I know it has dropped in the past somewhat.

Well then...... nevermind.

. That is a good drop.

Could look into salt mix closer to your parameters. Have the opposite problem with HW marine. 480 ppm CA with 8 ish alk.

PeaBrain · Mar 11, 2020

I just found my notes. The last batch I had, mixed to 1.025:

Alk: 8.6
Ca: 400
Mg: 1050

Magnesium was at 1050! I used Salifert tests so I am pretty confident in those readings. Could be a bad batch of salt. I will be sure to mix the salt in the bag before adding it to the water.

Quietman · Mar 11, 2020

Well there's another HW marine thing....mg is very high as well. Not really proposing one salt is better....think all the big brands are good. But perhaps the make up that was good starting out isn't the one you need now.

PeaBrain · Mar 15, 2020

I mixed new 30 gallon saltwater about a week ago and planned on doing a water change today. Things are doing well in my DT and I don't know if it is necessary; I'd hate to stress everything out now with a water change. Last change was two weeks ago.

Is there any harm in letting the new SW sit in the container for another week or so? It's heated with a power head to keep it moving.

Randy Holmes-Farley · Mar 15, 2020

PeaBrain said:
Just wondering if it's common to dose fresh salt water with 2-part and Mg to get the levels up to match the DT. I have noticed Reef Crystals falls short of Ca and Mg at 1.024 or 25. I think last time I tested the new water Ca was around 360 or 380.

It is not normal to need anything in Reef Crystals. Id boost salinity to 35 ppt, but even so, the values should be high enough.

ScottB · Mar 15, 2020

IORC mixes very high across the board for me at 35ppt. In the handful of occasions I have tested my mix, Salifert showed:

dkh 10
Ca 450
Mg 1300-1350

If I need to do a big WC, I have to knock down the dkh with Seachem acid buffer.

IORC saves for quite a while just fine. People say not to keep it moving but I do. There is always some residue but it never bothered me.