Water/Res question

I have started using only distilled water in my tank, which makes for very good PPM readings when it comes to food. However unlike with my tap tater, the PPM is dropping at a good rate.

I'm doing autos and they're almost done.

Is it ok to add small amounts food when I'm adding water if I keep the PPM reasonable. This is between tank changes.

Here is how you should do it:

Refill your rez with tap or distilled or whatever your using, back to the original water level. Test PPM and write it down. Now you know exactly how much PPM has been utilized by the plants.

Add a BALANCED amount of nutrients back in if your really worried about PPM levels. When I say balanced I mean, use the original ratio or micro, macro, boosters, etc.

Sometimes I add back nutes, some times I just let it be. What I mostly due, because I'm uber fucking smart AND lazy. I have a 25 gallon top off tank connected to my rez with a float valve set to fill when the the flood cycle drains my rez below a certain level. The top off tank is typically mixed at around 600 ppm and a ph of around 4- 4.5 depending on growth stage. That way.. my rez is always full, my PPM's always stay within 100 of the original number and my pH is rock solid stable, and I typically spend about 5 minutes a week maintaining the rez which consists of sticking my meter in there just to double check things are kosher.