if your using a hydrometer take my advice..

from the very begining i have had a refractometer....about a month ago i left it out an my niece knocked it off a table and it broke. at the time money was tight and i was just going to use a hydrometer for a few weeks......well i finally got a new refractometer and soon realized my hydrometer was way way out! it read 1.024 but in reality it was 1.031!! i had a major ich outbreak about 2 weeks ago and i believe it's directly attributed to the salinity spike.I caught it just in time... no loss of fish and the ich is clearing out as my salinity slowly returns to normal.. the lesson of the story is no matter what don't trust a hydrometer unless you want to slowly kill everything!

 

Glad to read that your no longer having an issue with ick. However, when a hydrometer is used properly and cleaned after used and given a monthly vinegar bath, your readings will be accurate. A number of people who claimed their hydrometer was off by a lot never cleaned the instrument. Jus like everything else, proper care is needed when using a hydrometer.

 

I use a hydrometer on my tanks, Have yet to have issues with water. I clean it after every use and use a bit of vinegar. Tank looks awesome. I am curious to one day splurge and get a refractometer ... will see though

 

Thats not always true. I tested my friends brand new hydrometer against my refractometer, and it said his tank was 1.024 and it was actually 1.027. So even brand new right off the shelf they can be wrong.

 

i find the hydrometer to be too much work, and guess work. i had such little confidence in mine, it would take 4 or 5 times to get a consistant reading. i always cleaned it too. the refractometer was maybe the one and only smart thing ive done in life to date.

 

You need to take a water sample that is 6" deep and hold the hydrometer level. The surface you set it on may be slanted. Temperature of your water will also change your reading. Hydrometers are calibrated to read correctly at 77F. Refractometers, if you purchase a temp correcting model, will account for the temp of the water. There is more user error when it comes to a hydrometer than refractometer. However, if the tool is not calibrated properly it will read incorrectly as well.

 

I was a deep six hydro, so yes it was done right. It was still off. He now has a refractometer. You can use a hydro, I did the whole time I had my first FO tank. But now that I have a reef I just don't trust them. With the amount of money we invest in our tanks why skimp on a $30 item that can literally save your tank?

 

I just take my hydrometer down to the LFS every couple months and they check it against their refractometer. that way i know how "off" my hydrometer is and can get a accurate measurement. not a perfect solution but it works well for me.

in my experience the hydrometer will be wrong but consistent (i.e. if its wrong by .005 it will always be wrong by that same amount)

 

just remember, the refractometer can also be affected by improper care and cleaning. I started cleaning the glass with RO/DI water after I realized salt residue from the previous use was actually increasing my readings by as much as .003

 

after each reading , i always use vinegar to clean, then rinse it off and dry it.