hi.the newer black aqua valves that still fit the 6mm pipe are sitting several mm higher on the t connector than my older blue aqua valves.this is causing the water level to fill to 25mm instead of 20mm and the level only goes down to about 15mm before the water refills to 25mm.the blue aqua valve let the plants drink all the water before refilling,these black ones are overwatering my plants.i use 40mm of clay balls in the bottom of pots