salinity dropping - any ideas why?

[Laurie]

Hi -

It's a 200 gal. tank - heavy coral population, medium fish population. Drip kalk 24/7 as top-off using a liter meter - approx. 6 liters per day. I also add homemade buffer about every 3rd day and some Turbo Calcium twice a week.

Salinity dropped from 1.025 to 1.020 - don't know over what period since I hadn't tested for a while. This is using a cheap swing-arm hydrometer but water change water tested at 1.026 so I think it is fairly accurate. The water level stays steady so I don't think I am adding too much fresh water and salt creep isn't that much.

Any ideas why this is happening? The corals all look fine so far but I know this can't be good in the long term. I am currently topping off from my water change water to gradually raise the salinity over the next couple of days but I will need to switch back to the kalk after that.

Any advice will be appreciated.

TIA - Laurie

 

[esmithiii]

How much water is your skimmer pulling out? The only other possibility (other than your hydrometer being wrong) is that there is a leak somewhere and the salt water is being replaced by freshwater...

Ernie

 

[Kelp]

My experience with the "swing arm" hydrometers is they are pretty much worthless. [BTW I have one for sale if anyone's intrested

]
Over time, your tank will build up crystilized salt around the edges, (leeching)
This occurs in the sump area as well- anyplace where evaporation occurs. I'm sure lots of people dispose of this excess salt directly into the trash- Usually its not a real sanitary looking accumulation. If you are cleanning this off and disposing of it, THAT is where your salt is going. This should be added back to the tank. Being careful not to land it on any living critters. (most of mine occurs in the sump area, and I just throw it into the sump. Good Luck HTH.

 

[SPC]

Lauri, my opinion is that what ever you are using to measure with is not accurate. I don't know if you have tried a Hydrometer yet, but I find them to be highly accurate. You might be able to borrow one from someone in your area to double check your readings.
Steve

 

[Laurie]

Thanks guys. I just ordered a refractometer (on sale for $70, BTW) from North Coast Marine. My husband is going to take a water sample to LFS today so we can get an accurate reading until the refractometer comes in.

No leaks, very little skimmate, very little salt creep. Only 6 liters per day are being replaced so that should not make such a drastic difference. I think it has to be the lousy hydrometer.

Laurie

 

[Gatortailale1]

Are you adjusting for water temp changes, or does your current meter adjust automatic for it?

Skimming will also remove salt over time.

Good plan with new meter.

C