Specific Gravity Of Your Marine Tank

[Fish Fingers]

Just out of interest, do you test SG with a hydrometer or some other device.

I use natural sea water in my reef system. Straight out of hte ocean and directly into my tank within 2 hours (sooner if possible).
The SG along the cornish coast in the UK is 1.025 and this is tested with a refractometer.



I had a terrible disaster in my old 100 gallon system with SG. I went a long time monitoring it with a Hydrometer and got a reading of 1.024. When i got my refractometer the true reading was actually 1.030 !! I had only placed an achilles tang in this system the day before. Within 4 days of its arrival it was dead and a mere husk of what it was. It turned from a very fat healthy ish into a skeleton. Now i know Achilles are very very delicate fish but the only reason i can see for its quick demise is the high SG (And the red sea is considered high SG). The SG was so high that it completly dehydrated the fish from what i can tell.
I then had to slowly reduce the SG of the system over a period of 1 month to get levels back to normal. The amount of stress that high sg places on a fish is very high indeed. I also see a good argument for running low sg so that parasites find it harder to acclimatise in systems.

That's why your meant to calibrate them .

I use a floating hydrometer. Remember guys I live no where near you, there is the possiblitity of our water being different S.G's! I don't know what the S.G is where your fish are collected from Navarre, but just because yours struggle in higher S.G tanks doesn't mean that all fish will! I'll withdraw my statement on the 1.028-1.030 thing as I can't find where I got it from. I must of just imagined I saw it but I could of sworn I'd read it somewhere. Oh well.

 

[steelhealr]

Swing arms can't be calibrated with certainty, especially when air bubbles can get stuck on the arm and throw the whole reading off. It's really just a bunch of plastic. IMO, measuring s.g. is one area in marine tank keeping that you should really try and not cut corners....invest in a refractometer.

Salinity is measured in percentage. Specific gravity is dimensionless. Salinity is not temp dependent whereas s.g is. SH

 

[crazyelece]

I disagree on this one. As long as you keep your tank temp consistant, a box hydrometer is very consistent. You just need to know how far off it is. Calibration can be done with a refractometer. I actually tested this when I got my refractometer. Over the period of two months, testing at least once a week, my refractometer was consistantly off 0.003 from my hydrometer. While I do think if you want to invest the money for a reef the refractometer is worth the cost, I think a calibrated hydrometer is fine for FO or FOWLR systems.

 

[petey Z]

well you guys are starting to convince me to get a refractometer, but i just wanna kno where i can get a cheap and reliable one??

 

[crazyelece]

EBAY. I think I paid $30 for mine.

 

[superman]

I disagree on this one. As long as you keep your tank temp consistant, a box hydrometer is very consistent. You just need to know how far off it is. Calibration can be done with a refractometer. I actually tested this when I got my refractometer. Over the period of two months, testing at least once a week, my refractometer was consistantly off 0.003 from my hydrometer. While I do think if you want to invest the money for a reef the refractometer is worth the cost, I think a calibrated hydrometer is fine for FO or FOWLR systems.

I gotta side with Steel on this one, I have had personal experience with swing arm hydrometers suddenly becoming unreliable. This makes no sense to me at all, even though the tank temp, salinity, clarity, etc. were all the same, in each instance the swing arm started to produce readings that were several points to high or two low (when compared to the calibrated refractometer) I for one will NEVER trust a swing arm unless it is then referenced by a refractomer. Ditch swing arms unless you are truly in a situation where accurate SG readings are not important and does not involve living things. Just my honest opinion.

 

[Mr Miagi]

Just out of interest, do you test SG with a hydrometer or some other device.

I use natural sea water in my reef system. Straight out of hte ocean and directly into my tank within 2 hours (sooner if possible).
The SG along the cornish coast in the UK is 1.025 and this is tested with a refractometer.



I had a terrible disaster in my old 100 gallon system with SG. I went a long time monitoring it with a Hydrometer and got a reading of 1.024. When i got my refractometer the true reading was actually 1.030 !! I had only placed an achilles tang in this system the day before. Within 4 days of its arrival it was dead and a mere husk of what it was. It turned from a very fat healthy ish into a skeleton. Now i know Achilles are very very delicate fish but the only reason i can see for its quick demise is the high SG (And the red sea is considered high SG). The SG was so high that it completly dehydrated the fish from what i can tell.
I then had to slowly reduce the SG of the system over a period of 1 month to get levels back to normal. The amount of stress that high sg places on a fish is very high indeed. I also see a good argument for running low sg so that parasites find it harder to acclimatise in systems.

I use a floating hydrometer. Remember guys I live no where near you, there is the possiblitity of our water being different S.G's! I don't know what the S.G is where your fish are collected from Navarre, but just because yours struggle in higher S.G tanks doesn't mean that all fish will! I'll withdraw my statement on the 1.028-1.030 thing as I can't find where I got it from. I must of just imagined I saw it but I could of sworn I'd read it somewhere. Oh well.

Ive run a search on RTAW (Aussie based forum) and it appears our NSW ranges from 1.025-1.028. Depends where the person is situated.

 

[ostrow]

26 for me, using refractometer. I don't callibrate it more than once a month. Test once or twice a week. Always test makeup water, of course. Absolutely essential for QT hypo treatments.

Swingarms are not accurate, and I found that callibration was not reliable ... the +/- on them is huge.

 

[bunjiweb]

I try to keep my 2 nanos at 1.026 although i have seen them higher without any noticable problems. I use a Swing-Arm Hydrometer, TMC Salt & regular tap water.

Ben

 

[huntnikk]

Wow... I haven't been around SW tanks that long (only since October) but I haven't heard until reading this topic of readings above 1.024

I use a swingarm floating hydrometer from Marineland LAbs.. and although it ranges from 1.000 to 1.032 the safe range it lists is from 1.020 to 1.024... Also the guys who work at the aquarium store I go to most often all seem to agree to keep the fish tanks at between 1.020 and 1.022

Mine tank seems to fluctuate between 1.021 and 1.023 depending on how much water I pull out at water changes... (I have my tank marked with tape at the 25% 50% and 75% levels)

The biggest thing with the floating swing arms is you need to make sure every single bubble is off the arm... I also always do my test twice or three times to make sure I get the same results (to offset bubble errors)