Sure, you also need light and food for your plants and fish, but water, the aqua in aquaponics, is the lifeblood of your system. Most of your aquaponics problems will be caused by poor water quality. So, it is vital that you keep your water quality as high as possible. There are several water quality factors you need to control. Let’s start with what I call the 3 H’s: pH, GH, and KH.
Start With Good Water.
It is much easier to maintain good water quality if you start with water of good quality. If the tap water in your home is not as good as it should be, you may want to have water delivered if it available in your area. of course, you should test that water before adding it to you tank.
If you have the time and patience, you could run your water through a reverse osmosis (ro) filter to remove all the bad stuff. If you have a large system and a small capacity RO filter, this might take days rather than hours to accomplish. What to do if you have to start with bad water!
Adjust the pH
The pH of water is expressed as a number that reflects the acidity of alkalinity of water. The number can ranges from 0 to 14 with pure water being a 7.0 which is consider neutral. Technically, pH is a measure of hydrogen ions in water. The p comes from a German word “potenz” or power. The H stands for hydrogen. The H is capitalized because it is customary to capitalize element symbols. But enough chemistry, what we need to know is what pH number we are looking for and what to do if our water does test to that number.
Fish can survive is a fairly wide range of pH but plants are a bit more fussy. For most of us, a pH range of 7.0 to 7.5 is a good compromise. If your water tests out of that range, you can add pH up or down products until you get to the right number. You should do this slowly, over a period of days, if you have already added fish. When you get to the target range, you can maintain it by adding a pH buffer. If you do add a buffer, make sure it is safe for both plants and fish.
Tap water in most cities will be 8.0 or above. This is done to reduce the risk of leeching harmful particulates from water pipes. Think Flint, Michigan. The tap water in my hometown, Las Vegas, Nevada tests between 8.2 to 8.4. It took me several days to adjust it to the pH I wanted.
Products to raise or lower pH are available in most pet stores, hydroponics stores, or online on Amazon. You will also find kits for testing pH in these places. You can use test strips, test kits, or test meters. The kits and strips may not be quite as accurate as a test meter. Test meters are not all that expensive, so you might want to invest in one of these.
Adjust for Hardness
The tap water in Las Vegas qualifies as “very hard. I think it is so hard that if you look closely, you can see small rocks floating in it! When I first tried to measure the hardness with a test kit with witch you keep adding and counting drops to a test tube until the test solution changes color, the number of drops got so high that I quit counting and concluded that, yes indeed, the water was hard.
There are two types of water hardness: general hardness (GH) and carbonate hardness (KH). General hardness (GH) is usually the measurement of calcium and magnesium ions in the water. General hardness is not usually a concern except that it will can leave unwanted mineral deposits on faucets, bath tubs, and toilet bowls. But your fish and plants do require these minerals for good health.
Carbonate hardness (KH) is the measure of bicarbonate and carbonate ions in the water. The important factor of GH is the effect it has on the pH of the water. Too high, and it will be difficult to lower pH, too low and the pH may undergo big changes which can be harmful to your fish. So we need it to be just right, a reading between 4 to 12 dKH which you can measure with an API test kit.
Other Water Quality Issues
Temperature, levels of ammonia, nitrites, nitrates, and dissolved oxygen are also very important in maintaining good water quality. We will cover those in other articles. However, if you get all your H’s right from the beginning, you will have a head start on maintaining good water quality in your aquaponics system.