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Old 01-13-2004, 01:15 AM   #1
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specific gravity table

ive noticed that my specific gravity can drop from 1.025 to 1.024 with as little as minus 1.5 gallon of water in an eighty gallon tank. is this real or is this an example of bad testing? or am i fretting over nothing? hence my topic, is there a table listing changes in specific gravity with losses or additions?
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Peppermint Shrimp:
Crush two tbs minced mint leaves (no stems) with the juice of two limes, two tbs of sugar and a shot of light rum. Marinade eight cleaned jumbo shrimp for two hours in fridge or overnight (overnight is best). Skewer and salt shrimp. Broil or grill over medium high heat until shrimp become opaque (apx. two and a half min per side). Serve with black beans cooked with garlic, green onions, bacon and topped with a slice of lime.
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Old 01-13-2004, 09:17 AM   #2
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sounds right to me !! not to worry imo
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Old 01-13-2004, 11:23 AM   #3
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How are you testing your SG? Refractometer or Hydrometer?

Are you saying your tanks SG goes down when you have evaporation?
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Old 01-13-2004, 01:06 PM   #4
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Quote:
Are you saying your tanks SG goes down when you have evaporation?
sorry, reverse that
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Peppermint Shrimp:
Crush two tbs minced mint leaves (no stems) with the juice of two limes, two tbs of sugar and a shot of light rum. Marinade eight cleaned jumbo shrimp for two hours in fridge or overnight (overnight is best). Skewer and salt shrimp. Broil or grill over medium high heat until shrimp become opaque (apx. two and a half min per side). Serve with black beans cooked with garlic, green onions, bacon and topped with a slice of lime.
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Old 01-13-2004, 03:11 PM   #5
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Oh ok. Thats what I figured.

How are you testing your water? For example swing arm hydomoters have some degree of error and two tests could turn up a different SG reading thats off by .01 or even .02
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Old 01-13-2004, 09:20 PM   #6
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How are you testing your water? For example swing arm hydomoters
yes a deep six hydrometer. my results are consistant.

i guess my question is if there is a table that explains additions and how they affect sg.for instance, say you have one gallon of water with a teperature of a and sg is b adding c amount of fresh water will lower sg to d. or at least something to that effect
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Peppermint Shrimp:
Crush two tbs minced mint leaves (no stems) with the juice of two limes, two tbs of sugar and a shot of light rum. Marinade eight cleaned jumbo shrimp for two hours in fridge or overnight (overnight is best). Skewer and salt shrimp. Broil or grill over medium high heat until shrimp become opaque (apx. two and a half min per side). Serve with black beans cooked with garlic, green onions, bacon and topped with a slice of lime.
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Old 01-13-2004, 10:20 PM   #7
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Salt only leaves your tank if you do a water change, salt stays in the water through evaporation.. which is why you top off almost every day with freshwater.


So if you take out to much water due to evaporation, Your Salt level will go up.


If you add more than your regular ammount of fresh water to the tank, then your salt will decrease.
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Old 01-14-2004, 04:59 AM   #8
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So if you take out to much water due to evaporation, Your Salt level will go up.


If you add more than your regular ammount of fresh water to the tank, then your salt will decrease
ah yes
but maybe someone has a table or an equation explaining this in mathematical terms? it would make creating water for water changes easier instead of guessing. also it would make udjusting salinity in the tank more predictable.
this would also allow one calculate the concentration of your salt mix as well as other things.

its the chemist in me.
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Peppermint Shrimp:
Crush two tbs minced mint leaves (no stems) with the juice of two limes, two tbs of sugar and a shot of light rum. Marinade eight cleaned jumbo shrimp for two hours in fridge or overnight (overnight is best). Skewer and salt shrimp. Broil or grill over medium high heat until shrimp become opaque (apx. two and a half min per side). Serve with black beans cooked with garlic, green onions, bacon and topped with a slice of lime.
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Old 01-14-2004, 09:40 AM   #9
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Quote:
it would make creating water for water changes easier instead of guessing.
There shouldn't be any guessing. If you keep SG at 1.025 and make up for evaporation with RO water, then your SG will remain at 1.025.

For water changes, make the mix at SG of 1.025.

I change out 12-15 gallons in my 125. I don't need to precisely measure the volume of water because whether it's 12 gallons or 15 or somewhere in between I just mix it to 1.025SG and then do a water change.

Different salt mixes require different amounts to achieve the same SG. Follow the directions and adjust as needed.
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Old 01-14-2004, 03:01 PM   #10
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For water changes, make the mix at SG of 1.025

so when you mix your water for a water change the sg is right on the first time? if its off do you guess how much more salt or fresh water to add.

so far ive gleemed that sg is the density(mass divided by volume) divided by the density of pure water at 60F (1.000). seeing that we are dealing with the specific gravity of water then you simply use its density only (mass divided by volume). adjustments are needed as temperature rises, the water expands there for becoming less dense.
therefore if you add 25g of salt mix to 1000cc of water at 60F the water weighs 1025g. 1025g/1000cc (m/v) the final product is sg of 1.025.

i will work this out myself and add it to this post later.
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Peppermint Shrimp:
Crush two tbs minced mint leaves (no stems) with the juice of two limes, two tbs of sugar and a shot of light rum. Marinade eight cleaned jumbo shrimp for two hours in fridge or overnight (overnight is best). Skewer and salt shrimp. Broil or grill over medium high heat until shrimp become opaque (apx. two and a half min per side). Serve with black beans cooked with garlic, green onions, bacon and topped with a slice of lime.
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