PH below 6 bad for plants potted in soil?

All the nutrients are still available in that PH range just may not be the optimal PH but it still works. IF the plants are still looking healthy I don't think its much to worry about. If the feed is indeed the thing dropping the PH it seems like it may not be buffered well and that's not ideal. Could ty a different brand for your next run or get in the habit of adding some PH up to your feeds. I am a bit confused on why your using a blue lab guardian unless your feeding a lot of plants and this is inside a big res. One other thing is that there could be something growing in the res that is eating something from the feed and is whats causing the PH drift downwards. Good advice about getting in a air stone and keeping the water oxygenated for any res.

You defiantly want to bring that up to above 6. I’m not familiar with those nutrients and their instructions but I know that the majority of nutrient manufactures tell you to pH adjust AFTER you mix everything together. I use RO water as well and my pH is very high, in the 8’s. When I mix my nutrients it comes down to the high 5’s. After everything has been throughly mixed, I adjust the ph to 6.3-6.4. Any pH up product will work for doing this just be careful as a little goes a long way. I hope this helps.

Well its not optimal somce some nutrients wont be ansorbed as good, as to tjat can leave alot of deficciences the. A lockout because there wasnt a defficiency from beginning so you get opposite efffect. Try uppimg tpur ph tp 6.2-6.3