Salinity

[FishVet]

This is about as basic as questions get, sorry.

I had a brain fart and couldn't remember where my salinity was supposed to be. So I googled. Stupid internets, I got two types of answers:

1. "Salinity should be 1.019-1.023. It's better for fish, prevents disease, and you'd be a moron if you went any higher."

2. "Salinity should be 1.025-1.026. That's the salinity of real seawater. What kind of idiot would use anything else?"

Um, so which one is right? Mine is 1.022. Am I a moron? Am I doin it rite?

[MPowell]

If I remember correctly what I was taught was that fish do prefer a lower salinity level like 1.022-1.024 and most corals prefer higher levels 1.025-1.026.

[Doug]

Actually, the numbers you are speaking of refer to specific gravity, which changes relative to temperature (as temp rises, SG drops). Therefore, the SG of one tank can't be compared to that of another unless their temperatures are referenced. Oxygen is more easily dissolved in salt water of lower specific gravity, so a fish only tank is thought to benefit from a lower SG like 1.020 or even slightly lower. Inverts do better at a higher SG.

[Gz28]

I thought our refractometers were temperature correcting?

[Doug]

I thought our refractometers were temperature correcting?

If I read correctly, a refractometer requires only a couple of drops of tank water for a reading. I can't quite figure out how that small amount of water remains at the same temp after it is removed from the aquarium. What if my room is very cold and my aquarium heater very efficient?

[Gerwin]

refractometers, at least the ones for aquarium use do claim to be temperature compensating, as of now I have no reason to doubt them. Some of the swing arm versions also now claim to be temp. compensating. But Doug is correct there is a correlation between temp and specific gravity with hydrometers that do not state to be temp. compensating

Also the biggest advantage in my book about lower salt for Marine fish is the reduction in parasite outbreaks

[FishVet]

For what it's worth, I put my heater in yesterday, and the cheapo wal-mart swing arm I have measured exactly the same at both 70 degrees and 84 (yes, I turned the heater down a notch this morning, that thing is EFFICIENT), and it matched Gerwin's refractometer reading, so they apparently correct for temperature.

I'll probably increase my salinity (very gradually) to the 1.025 neighborhood before I get some coral.

Thanks

Dominic

[Doug]

If you're saying your temp went up 14 degrees in one day, and you have fish, I would recommend you bring it back down to your desired temp in very small increments, like a degree every couple of days. That big, fast jump should already have them stressed. Watch for signs of parasitic outbreak. Increase aeration in the interrim.

[FishVet]

No worries...no fish in the tank yet. It's a new tank. Only things stressed are me and my bank account

Really shocked me that the heater brought the temp up so fast, I didn't think it could do that. But I'm home this afternoon and it's back down around 79-80.

First fish will be introduced SOON! As soon as I know that the temp and water chemistry is stable.