With so many dedicated new members, and the mountain of information, I thought I'd summarised my 6 most critical water parameters I frequently test, to ensure my shrimps have the best possible water quality. GH (General Hardness) GH is the measure of Magnesium (Mg+) and Calcium (Ca+) ions in water. Water described as “soft†or “hard†is in reference to GH. GH is measured in dH, and 1 dH is approx.. 17.5mg/L (ppm) 0-4 dH (Very Soft) 4-8 dH (Soft) 8-12dH (Medium hard) 12-18 dH (Fairly Hard) 18-30 dH (Hard) KH (Carbonate Hardness) KH is the measure of carbonates and bicarbonates in water. KH measure the alkalinity (buffering capacity resulting in the resistance of a PH fluctuation). KH is measured in dH, and 1 dH is approx.. 17.5mg/L (ppm). The higher the KH the more stability and resistance PH will fluctuate. pH (Per Hydrogen) pH is the measure of the balance of Hydrogen (H+) and Hydroxide (OH) ions in water. The pH scale goes from 0-14. pH reading of 7.0 is neutral, 0-6.9 is Acidic, and 7.1-14 is alkaline. pH is also a function of KH and CO2 concentration. Nitrates Nitrates are critical to our beloved shrimps, and often utilized to indicate the level of water quality once a tank is cycled. Nitrates between 0-20ppm should be our goal. Nitrate should be tested/checked frequently, as high nitrates can/will lead to shrimp deaths even weeks after the event. TDS/Ec TDS (Total Dissolved Solids)/ Ec (Electrical Conductivity) is essential to ensure overall purity of water. A TDS reading measures contaminants , but also minerals such as calcium, magnesium, and other trace elements and metals. The TDS reading of most natural clean spring water is approx. 100-200 ppm. RO (Reverse Osmosis) water will have approx. 0 TDS, and by adding essential salts/minerals to the required TDS/Ec,, this will ensure our shrimps have the purist of water with the right/essential minerals. http://www.shrimpkeepersforum.com/forum/showthread.php/3078-Dean-s-(Ec)-vs-BlueBolts-(TDS) Temperature Water temperature is a critical factor, and depending on the type of shrimp, a higher/lower range can be tolerated, but does add stress to the shrimps. Ensuring no sudden fluctuation, and maintaining the recommended level will ensure the best survival/breeding zone for our shrimps. There are many breeders using varying WP (i.e. soft water vs hard water, low PH vs high PH...etc)...please do your research and/or ask the forum members of their experience/knowledge, depending on the shrimp species you intend keeping.