HIGH Specific Gravity

trippclark

trippclark

Member
I have been using a SeaTest Specific Gravity meter that I bought about 10 years ago ever since I bought it. SG has, in recent months, been reading 1.024-1.025 (an increase from my former levels of 1.022-1.023). Since this one is old, and occasionally "sticks," I decided to buy a new one tonight. I bought an Instant Ocean hydrometer with a much wider range (1.000 - 1.032 compared to 1.017 - 1.027 on my old meter). The new meter is reading much higher, and shows my level at 1.030. :scared:
My inclination is to trust the new gauge. So, I guess I should take steps to gradually lower my SG, right? What are the dangers/symptoms of having such a high SG? Thoughts?
 
terrance

terrance

Member
Use r/o water or distilled to top off your tank when there is evaportion, dont use salt water, that would increase your salinity. Lower it slowly though
 
trippclark

trippclark

Member
Yes, I do this already. My thought is to mix water changes "weak" for a while (maybe 1.020 or so) until it drops. I might also draw out a little saltwater every couple of days and add fresh deionized water. My thought is that I should probably drop it the .005 that it needs over a two week period or so. Is that too fast/slow?
I am really curious to know what problems I may be causing by the higher than preferred SG. Does this cause noticeable stress to fish and inverts? Impact on algae? Anything else?
 
trippclark

trippclark

Member
Not a bad thought, but a refractometer is outside of the budget right now. I am taking BOTH hydrometers to the LFS today and I will have them check it against "known" levels there (I am hoping that they use a refractometer) so that I can tell which one is closest to correct.
I am still really curious to know what problems can be caused by the higher than preferred SG. Does this cause noticeable stress to fish and inverts? Impact on algae? Anything else?
 
birdy

birdy

Active Member
You also have to adjust the hydrometer to the temp of your water, I believe they are set for SG at 75 degrees F. if you run your tank warmer then there is a difference in SG. I don't know how to figure it out. I think Bang Guy does. In the very least test your hydrometers against a refractometer.
 
bang guy

bang guy

Moderator
Take both hydrometers to a fish store and compare the results with their refractometer and write down the differences. You should do this every 6 months with a hydrometer. Most hydrometers are inaccurate but they are usually consistant so if you compare them you can get accurate results.
 
D

daniel411

Guest
Just so you know, you can find refractometer's for around $39 if you look around online.
 
trippclark

trippclark

Member
Well, I took both Hydrometers to the LFS. Not much help, but they did try. They also use a hydrometer and do not have a refractometer. They tested theirs against mine, and in the process the "arm" fell out of my old one and down a drain in their shop -- so now I am down to 1 hydrometer (the new one that reads high). Their readings also showed this one to read high. I looked in the dry goods section at SWF.com and they have a refractometer on sale for $49.99, so I bit the bullet to solve this question once and for all. It is still not in the budget, but what the heck; I put it on plastic and I can pay for it next month! How difficult are refractometers to use? Is there calibration involved?
 
bang guy

bang guy

Moderator
Calibrating is really easy. You can just use RO/DI water and adjust the reading to 0ppt.
To use it you just put a couple drops of tank water on the plate and look through the viewer. Piece 'o cake. Just ignore the S.G. scale and shoot for 35ppt on the Salinity scale.
 
petem

petem

Member
I just used my new Deep Six Hydrometer today. Just filled up my tank and it's reading around. 1.025 The instructions mentioned to fill it with tap water and let it sit for 24 hours inorder for it to "self calibrate" But they also said it was calibrated in their lab, and each one has a specific calibration number. I guess with all these different variables, a refractometer would be good to have. But, would a refractometer give different readings based on the temp of the water also?
 
bang guy

bang guy

Moderator

Originally posted by PeteM
But, would a refractometer give different readings based on the temp of the water also?
This is a great question. ATC Refractometers are the most popular and they adjust for temperature within reason. Refractometers measure Salinity though... not the Specific Gravity. Actually, this is a good thing because it's the Salinity that really matters and not the S.G.
Bottom line - The S.G. will probably be wrong on a Refractometer but the Salinity (the measurement that really counts) will be within 1.0 ppt (for most refractometers).
 
D

daniel411

Guest
bang,
Do you know why there is such a huge difference between prices of refractometers? Even some sites will have ATC's at 40-50 and than others at 100-350? Is there some quality/accuracy issue? I went with a cheap one, and haven't as of yet had any problems with it.
 
bang guy

bang guy

Moderator
Better case, calibration fluid, better metal, etc. Not relly more accurate though.
Why are some cars $20,000 and others are $60,000?
 
jrpage

jrpage

Member
I too bought the one SFW.com has on sale. Hopefully there will be no more probs with salt retention or the lack thereof!
 
squidd

squidd

Active Member

Originally posted by Bang Guy
Better case, calibration fluid, better metal, etc. Not relly more accurate though.
Why are some cars $20,000 and others are $60,000?
I don't know...Why are some skimmers $189 and others $499...:thinking:
 
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