Salinity/Specific Gravity way to high

[Jon]

I just bought my first refractometer and found out why these are preferred over hydrometers. My hydrometer was reading my salinity at 1.26 specific gravity at 1.026, which is good for my reef tank, but when I checked it with the refractometer it reads 1.35 1.035 I am going to do a 15 gallon water change tomorrow and was wondering what my salinity should read in the new batch of water to bring my levels down. My tank is a 58 gallon oceanic with a 20 gallon sump.

Thanks for your input - Jon

 

[saltwaterguy112]

Re: Salinity way to high

Not to get all complected i would just add tap water to bring down to desired level.

 

[hijinks]

Re: Salinity way to high

take out 5 gallons and replace it with fresh water.. wait 30 minutes till the water mixes in and take another reading.. continue with small water changes till it comes down to the reading you want

 

[redfishbluefish]

Re: Salinity way to high

Jon, the skeptic I am, why are you blaming the hydrometer? Has the refractometer been calibrated? It would be nice if you could verify which one is giving you the bogus number by testing someone else’s tank or using their refractometer to see which one is correct.


Once that is determined, and assuming you are too high, I’d remove some water and slowly start to add back fresh. When I say slowly, over a multi-hour period. I’d start a siphon with a ¼ line with a knot to drip the water back into the tank.

One more point…you left out an important zero….1.026 and 1.035.

 

[pgordemer]

Re: Salinity way to high

Your tank inhabitants have been used to that high salinity for awhile, there is no overiding reason to reduce it quickly, (an actually doing it fast can bring on a host of problems). Just bring it down over a couple of weeks by doing water changes with a lower salinity water (try 1.022 for the water change), once you get back down then all future water changes can be a 1.026.

 

[Jon]

Re: Salinity way to high

The refractometer has been calibrated and appears to be working correctly. It was very easy to adjust... I am going to take out five gallons of water today and will add 5 gallons of RO water. Than when I do my water change tomorrow I will use only 10 gallons with salt mix to bring the levels down slowly. Than once that has setteled I will check the levels again on Sunday and will continue to take water out and add more RO water in slowly. Thanks for the advice.

 

[blange3]

Re: Salinity way to high

The refractometer has been calibrated and appears to be working correctly. It was very easy to adjust... I am going to take out five gallons of water today and will add 5 gallons of RO water. Than when I do my water change tomorrow I will use only 10 gallons with salt mix to bring the levels down slowly. Than once that has setteled I will check the levels again on Sunday and will continue to take water out and add more RO water in slowly. Thanks for the advice.

I suggest you reread pgordemer's post and take the slower route, unless the livestock shows signs of stress.

If they do stress, I would still use saltwater at a lower sg (1.020-1.022)and increase the frequency of water changes to every other day until back to 1.026.

 

[pgordemer]

Re: Salinity way to high

I am going to take out five gallons of water today and will add 5 gallons of RO water.

Thata huge amount of RO water for a tank of that size, your tank inhabitants are going to be upset with a change that fast..

 

[stcreef]

Re: Salinity way to high

What did you use to calibrate the refractometer. If you used RO water, it may not be reading correctly.

 

[Bryan]

Re: Salinity way to high

With a specific gravity of 1.035 the fish would have a hard time swimming at the bottom of the tank. Adding that much salt would have the same effect of being at great depthes. Good for anglers bad for reef fish.
If this is wrong (i am no chemistry Major) please let me know but it just sounds deadly for reef fish to me.

 

[Hawkeye]

Re: Specific Gravity way to high

Just a minor point which Bryan noted - the quotation of 1.026 is a known as specific gravity. Salinity is measured in ppt.

So you could say your salinity is 35ppt.
Or you could say your sg is 1.026.

anyways - good luck! no matter how you decide to resolve this - just go slow. The inhabitants are probably not happy about the high salinity but they are used to it. Dropping it down quickly could potentially make matters worse.

ps redfishbluefish - good catch on the SG missing a zero. I fixed the original post.
pps. thanks for the catch on the "parts per thousand".

 

[redfishbluefish]

DON’T DO ANYTHING WITH YOUR TANK YET!

Something just hit me…..ouch! My brain started to work. The number Jon originally supplied might be right….that is, if it is actually a refractometer that is giving him the “refractive index,” not the “specific gravity.” The ones most of us buy are actually specially made for saltwater and marked off as “specific gravity,” but in fact are measuring refractive index (with specific gravity marking). If it is a true refractometer, a number of 1.35 is not that far off for the proper salinity for salt water. He might have (almost) good stuff.

Jon you need to read the manual that came with your refractometer to see if it is showing you specific gravity (made especially for salt water), or refractive index (what a chemist would use). If the number you originally reported is correct….1.35…I’ve got to believe you are reporting refractive index. If this is the case, your target refractive index is 1.3394….that equals a specific gravity of 1.026 (for salt water).

 

[Jon]

Thankyou everyone for all of your input. Around 2pm today I did a 5 gallon water change of RO water only. I let the tank cycle for a couple of hours than I tested the salinity. My salinity dropped from 1.035 to 1.030. My alkalinity and magnesium also dropped but I dosed them accordingly to bring the levels back up to par. The one strange thing that did not change was my calcium. It is reading 440 which is where it was a couple of days ago. This doesn't make sense since I took water filled with nutrients and replenished it with regular RO water. Anyway everything seems to be doing fine with no signs of stress at all.

Regarding the one post about which refractometer I own I just bought this from Marine Depot and it is designed for the saltwater aquarium. It reads the salinty on the left side and the gravity on the right hand side. I am certain that this is an accurate reading it is giving me.

As of now I am going to monitor my tank and my nutrient levels on a daily basis and will probably do one final water change next week. I plan on doing a 10 gallon water change but using only half of the correct amount of salt. This should bring my levels down another 5 points and will bring the salinity around 1.026

 

[calaxa]

Jon,

Next time do not perform such a drastic SG change in a reef tank. It is no problem for most fish but inverts don't like such massive changes in SG.