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#21
04-10-2006, 10:56 PM
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1.023
Im at 1.023 but I dont have a refractometer. God only know how off the old swing arm is.
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#22
04-11-2006, 03:11 AM
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Just wondering, to anyone who knows...why is the SG at 1.025+ prefered?
I'm a fisherman and whenever we have to deliver our product alive, we keep the SG between 1.019-1.021. We dont keep it lower to save on money because we use different salt than aquariums. Our prawns have no problem in the tanks and can live in a plastic fish tote (equivalent of about a 65G tank) for 40+ hours with 150-190lbs of prawns inside. The SG levels and temperature are dictated by the company that buys the prawns because those are the perameters of their tanks. When we measure the SG of the ocean water (taken from approximately 15 feet down) it reads around 1.015-1.018, depending on location of course. Any explanation or ideas? I'm sure its something simple and i'm just overlooking something obvious. -Cam
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#23
04-11-2006, 03:17 AM
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Temperature plays a part in measuring sg and salinity. I don't know how much difference it actually does make though
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#24
04-11-2006, 03:21 AM
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Noj,haven't thought of that question in a while but if memory serves me. I believe 1.025 is the average SG with some places lower and others higher.
__________________
No matter how hard you try, you can't baptise cats.
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#25
04-11-2006, 03:48 AM
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Cam, the value of 1.026 is the average SG of the reefs our corals come from. This value also corresponds to the correct values of Ca (and all other elements, really). Lower salinity means lower everything else (in nature).
I've also tested the water locally and SG is much lower. pH is under 8.0 also, mostly due to FW run off close to land. Can your prawns live in this for a while? Sure. Long term, maybe, but not optimally.
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Brad
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#26
04-11-2006, 03:54 AM
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Thanks Brad.
Our prawns are also kept in 35-38 degree farenheit water too. So the SG doesn't need to be optimal because of the amount of oxygen they are actually consuming at those temperatures. I know the Fraser River plays a HUGE role in how high the SG is between Vancouver Island and the mainland. The difference between high and low tide within 20-30 miles of the fraser is around 1.012 on flood, and 1.019 on ebb. Pretty remarkable really. All quite interesting, thanks for the explanation! Last edited by Noj; 04-11-2006 at 03:57 AM.
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#28
04-11-2006, 02:55 PM
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1.024 area on my guage (which i think the guage is alittle low itself as lynn's guage showed my salt higher at 1.026) - although i would like to get a refractometer i figure keep what i have been doing as everything is happy and if i change to something new i will probibly end up screwing it all up
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