Plumbing question and salinity question

[gradoj]

I have a couple of questions:

1. Lots of pumps have 1/2" connectors. What size pipe/tubing do most people use for returns from their sumps?

2. What do people use to measure salinity - refractometer, specific gravity measuring device or a conductivity meter?

3. I found a refractometer on ebay but I'm not sure if it is suitable. It boasts a range of 0-10% and an accuracy of 0.10%. I assume this is measured and specified as a refractive index. Can anyone tell me what these values would correlate to in specific gravity?

TIA

[AndyL]

1, Basically easiest way to size returns is to use the calculator on reefcentral, while 1/2" may be enough to get water up to the tank, when it's mixed with air returning (as are most) you generally need bigger. And usually you step up even further expecting future upgrades ;)

2. refractometer I find to be easiest, somewhere around here I have a old fashioned IO hydrometer - but it was rather annoying to use I found.

[Bartman]

Make sure the refractometer on eBay is for measuring salinity and not for sugar or some other substance. I got this unit for about $37 USD:

http://cgi.ebay.ca/NEW-Salinity-Refractometer-4-Aquarium-Pond-Hydrometer_W0QQitemZ7771440809QQcategoryZ20755QQrd Z1QQcmdZViewItem