# Salinity question



## fishykisses (May 11, 2010)

So I have a 55g marine tank I'm just setting up.
I have about 60 lbs of LR, 10lbs of rubble in a Rena filter...it's the one with the 4 baskets and it's been running just over a week. Next week my lights and skimmer should be here, for now I'm just using a fluorescent light. I will have 270wpg and the coralife 65 skimmer. 
Now that you have the background... My salinity went up mid week for some reason. It was at 1.023 and then it shot up to 1.028, I did a water change and swapped out about 7g's of water. The salinity is now 1.025. 
Should I leave it at that or do more wc and add more fresh water?


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## Rastapus (Apr 21, 2010)

This is a valuable question for a number of reasons. Firstly, your salinity will not climb on its own unless you are topping up from evaporation with saltwater. All top ups should be with FW as your salt does not evaporate. Another possibility is your hydrometer may be faulty.
To answer your salinity level question, most hobbyists maintain a lower salinity in efforts to help prevent the presence of parasites. Although a lower salinity has proven to have some affect on this, it is more common in a wholesale situation where many fish are kept in one system. Lower salinity will increase your dissolved Oxygen levels which will be beneficial to your fish, in theory. The ocean salinity is roughly 1.026 as an average. It generally will not measure below this. One might argue that having conditions closer to their natural habitat would be more beneficial. Recently we have discovered through our experience that higher salinity with fish seems to be beneficial as well although the reasons are not yet clear as to why. 
Sorry for the long answer but it was a good question that most usually give the response of what they keep theirs at with no real reason why. IMO keep your salinity around 1.026 or slightly higher and make sure you are using a high quality hydrometer or better, a refractometer.


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## fishykisses (May 11, 2010)

I have a feeling it shot up because the salt hadn't fully dissolved when I first set up. Thanks for lengthy response, getting into sw is a huge learning curve and any and all info is greatly useful and beneficial!
I'm not going to be adding fish any time soon but when I do, if the fish at th hop ar kept in low salinity and mine I higher, how would I acclimate them? I know they tend to be much more sensitive than freshwater fish.
Thanks so much


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## gklaw (May 31, 2010)

As Grant has suggested, make sure you have a good hydrometer, or the more expensive refractometer. The salinity reading could be affected by fluctuation in temperature as well - not sure by how much. I used to like the glass hydrometer but I keep breaking them so I finally bough a refractometer. My only confession is that I probably have not used that for *at least* a couple of years.


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## Rastapus (Apr 21, 2010)

fishykisses said:


> I have a feeling it shot up because the salt hadn't fully dissolved when I first set up. Thanks for lengthy response, getting into sw is a huge learning curve and any and all info is greatly useful and beneficial!
> I'm not going to be adding fish any time soon but when I do, if the fish at th hop ar kept in low salinity and mine I higher, how would I acclimate them? I know they tend to be much more sensitive than freshwater fish.
> Thanks so much


There are two ways. One is to quarantine the fish in another aquarium but most hobbyists don't. 
When acclimating from a shop, the common practice is to place the fish in a small bucket and slowly add water from your aquarium to gradually mix your water with that of the store. This is a good general practice regardless of the source of the livestock. This can be done with a simple piece of airline tubing draining by gravity into the bucket. A small air valve or not in the tubing can regulate the flow.


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## Chewie (Jul 21, 2010)

*lights*

Did you say you will have 270 wpg of lights? 270 x 55= 14850 watts. Or did you mean total of 270 watts. 270 / 55 = 4.9 watts per gallon. Sorry just saw it and got curious. I keep my salanity @ 1.025 @ 79°


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## SeaHorse_Fanatic (Apr 22, 2010)

Skip hydrometer & shell out for a refractometer. I've known reefers who lost their whole tank because their hydrometer was inaccurate and their salinity was waaaaaay off.


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## fishykisses (May 11, 2010)

270 watts...


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## Ebonbolt (Aug 12, 2011)

+1 on the refractometer; the difference in SG could have been caused by a faulty hydrometer. Refractometers aren't cheap, but it's better to spend now then to have to replace thousands of dollars worth of fish and corals in the future cuz the hydrometer wasn't telling you what your specific gravity really is.

Not to be picky, but it's actually specific gravity you're talking about; salinity is measured in ppt; S/G is measured as a 4 digit decimal that starts with 1.


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## fishykisses (May 11, 2010)

done! just got a refractometer off ebay for $28!


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## fishykisses (May 11, 2010)

i got my refractometer in the mail last week and tried it out today.
Big difference and i'm wondering if i calibrated correctly or if there really is that big a difference between the hydrometer and the refractometer.
Hydrometer reads 1.027, Refractometer reads 1.023. 
I think i may take a sample to my LFS and get them to test and see. that seems like an huge difference!


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## babyreef (Nov 10, 2011)

A refractometer is only useful if it is calibrated properly, I highly recommend buying a calibration solution 35 ppt (around $5) since that is closer to your target salinity. Most people just use RO/DI or distilled water to calibrate at the 0 ppt mark. Very poor way to calibrate IMO. I do both but rely on the 35 ppt calibrated solution primarily.

Also, dosing can effect salinity readings on a refractometer or hydrometer. You are increasing the density of the water with everything you add (not by much however).

Always make your SW in bucket and let it sit over night, test it at the temperature you keep your tank (use a heater in the bucket) before doing a WC. I think this is why you are getting your fluctuations with your salinity.


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