Live rock drop salinity?

So I added 20 lbs live rock last night to my 38g Nuvo and it dropped my salinity which had been stable for like 4 days this morning...? Is that normal? Also, do I really NEED 38 lbs? There's no room to put another 20.

 

Rock wouldn't drop salinity. In reality, you can add or remove as much rock as you prefer. The purpose of rock is to provide a means and location for nitrifying bacteria to reside. So, it's a biological filter. The less that is available, the less bacteria to establish. So in reality, it's up to you how much you add. Some hobbyist run saltwater aquariums with zero rock. However, they resort to some other means of filtration.

 

How big of a drop are you talking about? Check your tank for salt creep...which is water dripping outside of your tank somewhere. What about topping your water off..this too can cause a drop in salinity. Wet skimming will cause a drop also.

 

On my little salinity thing, it said 34ish the last 3 times I checked it and this morning it was about 26. And it did displace some water since it is a lot of rock..

 

what "salinity thingy" are ya using?

 

Coralife deep six Hydrometer

 

Thats wierd just top off with saltwater alittle at a time and bump your levels up slowly

 

yup..

 

Before you start topping off with saltwater, have your salinity tested by someone that has a refractometer. Hydrometers are notoriously unreliable. If they're not cleaned properly, the needle can stick, and most of them don't read accurately to begin with. Refractometers are more than worth the $40 or so you'll spend on one.

 

I disagree with the above statement about Hydrometers being unreliable. They've been used for many many years way before refractormeters ever became available to the public consumer. With much success I might add. If taken care of properly and as directed they are reliable, period.