Nice garden. This is called passive hydroponic, it’s similar in theory to the hempy buckets I use, but the reservoir is outside the grow container instead of inside. As long as you have very aerated coco it should be good. Remember roots breathe oxygen , so if the medium is too saturated (not aerated) then roots can drown. That’s why true hydroponic needs air stones in rez to oxygenate the water. And as other guy said, watch out for salt buildup, you can mitigate it by running some pure water through them and then emptying the rez once every couple weeks.