[Ellery]

Jaine,

Here's a break down of the water testing technology based on cost:
1. Cheap - Simple Chemical Titration Test Kits (As mentioned pending brand will bring varying results.

2. Digital Photometers; (For example Hanna Checkers) are a mix of chemical and spectrophotometric but is very accurate and repeatable but more costly.

3. Most expensive - Continuous Reading monitors (Apex Controllers w/ proper probes, or single Pinpoint Monitors)

4. Latest Technology from startup company Mindstream Monitors. I've signed up to Beta Test one of their units. This would be game changing.

If you're looking to automate the aquarium industry you can check out my 5 part series of articles on http://www.saltwatersmarts.com/reefi...on-monitoring/