Basic Chemistry Question

[ggk1988]

I never encountered this issues before so I figured New to the Hobby was the place to post. My cycle was completed last week and I added my first coral. It is doing great. Today I got my salifert test kits in the mail and tested my water. Parameters are dKH 8.6 Mg 1470 Ca650 ammon/nitrite 0 nitrate 5 temp 79 and sg 1.025. Everything looks good to me except mg and ca are high. I am using reef crystals, just like I always have. No additives. Do i just need to wait until I put more coral in that will use the mg and ca in the water? or do I need to do something else to bring it down. My instinct is that high is better than low because there is more available nutrient to the coral in the tank but I could be wrong. Any input is appreciated.

 

[nlgill13]

650 ppm seems pretty high for reef crystal. As for Mag 1470 is pretty common....I actually had a problem with a batch that had a Mg of 1600+. It eventually came back down. Adding more coral should bring your levels down.

check this out:
http://www.reefcentral.com/forums/showthread.php?t=2393342

 

[ggk1988]

650 ppm seems pretty high for reef crystal. As for Mag 1470 is pretty common....I actually had a problem with a batch that had a Mg of 1600+. It eventually came back down. Adding more coral should bring your levels down.

check this out:
http://www.reefcentral.com/forums/showthread.php?t=2393342

thanks for the info. i thought it seemed high so I tested it twice with the same result. I never though I would want my salt mix to be deficient in elements but I think it would be easier to dose two part to bring my levels where I want rather than worry about adding too much with water changes.

 

[Randy Holmes-Farley]

IMO, if you mixed a whole bag or bucket of salt mix, it is reasonably unlikely those are accurate numbers for RC, but I suppose it is possible. I'm frequently more inclined to believe that big name salt mixes are reproducible than is the use of test kits by typical hobbyists. If you mixed just a small part of a container, it may have separated.

How are you measuring salinity? Higher than normal salinity will push calcium and magnesium up.

In any case, the values likely won't hurt much, and I'd just use a different bucket for your normal water changes. Try using normal IO, which is what I use anyway.

 

[downbeach]

Is your salt mix in plastic bucket? If so, there have been some reports of the elements separating into their respective grain sizes during shipping. It would be a good idea to mix the contents before use. What do you use to measure your SG? If it's a swing arm type hydrometer, or an uncalibrated device, your readings may be off, causing you to add too much salt mix, and by extension too much Ca, Mg and alk.

 

[ggk1988]

Refractometer calibrated before use using the calibration liquid. The mix came from a bag. I have used almost the entire bag since it only makes 50 gallons. I have made about 40 gallons of saltwater with it now.

 

[dkeller_nc]

A comment about refractometer accuracy - you might (or might not) get different readings if you place the refractometer and calibration solution inside your sump cabinet for 30 minutes or so before verifying/calibrating the unit. While some units are advertised as automatically temperature corrected, I'm personally suspicious of this - it's easier just to bring the instrument and any calibration solutions to close to the temperature of the tank.