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Specific Gravity Waaaaay too high

Supporting Member
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Apr 26, 2007
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Traded for a refractometer at the meeting. Thanks Charles, right? Tested my water and the sg was 1.030.
Tested the unit with the calibration fluid and it was right on. Should I bring this down gradually or all at once. It's going to take a big rodi water change to bring it down that far. Any thoughts? TIA
 
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Nov 10, 2007
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What size tank do you have? I keep my tank at 1.025 so if you do two 25% water changes within one or two weeks you can have it down to .025 in no time, what SG do you want it at?
 
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Little 40 gallon tank. 1.025 is the norm, right?
 
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Yea, Corals like high SG where's fish need for it to be a bit lower for parasite control (from what Iv'e heard).
 
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Target 1.024-1.025.

Zoas can close up and shrink with high s.g. Tyree said that above 1.025 is not so good for SPS colors.

For fish you can bring down s.g. pretty quickly. Slower is better for corals.

If you have 40 gallon system volume and you replaced tank water with fresh water a gallon at a time, you'd get something like this:

39/40*.0300=.0293
39/40*.0293=.0285
39/40*.0285=.0278
[...] .0271
[...] .0264
[...] .0258
[...] .0251
[...] .0245

You can recalculate based on other volume replacements.
 

Ibn

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That's interesting. I've been running my tank at 1.025-1.026.
 
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Thanks for the info. Yea, my zoas have been closing up for a while now.. I hope things improve soon!!
 
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Good reference on refractometers:

http://reefkeeping.com/issues/2006-12/rhf/index.php
 
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