most of my breeders are on the water paramaters you are stating , i just dump a box of bicarb straight into the water tanks everytime it rains as it puts the ph around 6.6 , and no worries i use the gold and white macrapore , rainwater can be good or bad , depends on where u live and where it was collected before being dumped on you , to increase hardness i use a pool hardner from the pool shop , around $10 a bag raises gh and kh and very cheap about 2 kilo in the bag i think