Question: “I make a fresh batch of nutrients & adjust my ph to the level I need. A day or two later I check my pH and it is out of acceptable range. What causes this and how do I fix it?” Your pH will fluctuate for a number of reasons. The largest factor is that the nutrient is mixing with outside elements every time you water (your plants, trays, pots). If pH fluctuation is happening too frequently, you should try a larger size reservoir. Remember as your reservoir water level drops your PPM increases. This is because your nutrient is becoming more concentrated by water loss (your plants do not eat all of the nutrients, during water loss the PPM goes up proportionately). If you have an automatic topping-off float valve, it’s your water causing the fluctuation (the new water topping off will not be pH adjusted). If you tend to have undesirable city or well water to begin with, this could also be the cause. Check the PPM level of the regular tap water at your housel with the TDS meter. This is a good test for water quality when wanting to know if there is a large amount of anything present. Good water will read 0-150 PPM. I’ve seen tap that is as high as 450 PPM, with a super basic level of 8.5! In any case it is good to buy a water filtration system if you experience any regular fluctuation of pH or if you notice there is a high PPM right out of the tap. Try to get a 3 stage RO (reverse osmosis) system for best results.