SG of atlantic ocean?

[MT79]

I have a deep six hydrometer. Today I took a sample of water from the beach in Virginia brought it back home w/ me to test for "hmms and hahs" so to speak. My hydrometer read sg 1.013. I run my tank at 1.024 according to the same hydrometer. Does the atlantic have a low sg, or is the hydrometer that far off? Anyone ever test water from the Atlantic? PS- I know I should get a refractometer but it just not in my budget for a month or two. Any info. appreciated.

[darb2]

I tested water from the Atlantic years ago, and salinity was 34 ppm. If you collected the sample recently, there are a few factors involved.
1. It is spring, lots of fw runoff from land.
2. It has been a wet spring around here.
3. how far off shore did you get your sample, and at what depth? Salt water is heavier than fw, so it sinks a bit, the fw from land when enters the ocean it over rides the salt water.
4. one sample is not enough. When sampling, I used to take 4 or 5 readings from the same area, and average.
hth

[jackdp]

Also, at this time of year in the philadelphia/jersey shore area the water temp is around 49-50 degrees fahrenheit...even though a deep six hydrometer claims to be temp compensating, I doubt it is accurate at those temps.

[MT79]

Final results: sg 1.013
Alk 2 meg/l
Ca 250
Seems ionically balanced. As mentioned there was some rain and this sample was taken near shore in VA. Water temp. was 72 when tested.