I used to do RO then I found out about RO changes lowering Ph so I switched to tap.. Sometimes half tap/half RO.. I don't feel I need the drip trays because with that powerful of a pump and those buckets being so narrow those spray bars hit every side of it.
Trevor- Blue bag. Solar salt. Accept no substitutes. Your rays deserve the best salt $6 buys.
As far as the drip plates... You should need them, but since you only have 2 buckets instead of 4 then you may not. That kinda flow needs some media area to disperse it. However... There will always be an arguement in regards to water coverage in wet dries.... This is why you add a bioreactor in addition to the wet dry
your ray were stressed from ammonia and are being stressed by your cncern. if levels are ok they probably need a little time. i was having higher nitrate with 0 ammonia and i found lots of nitrates in my tap i have been using nitra ban bags it takes alongg time but nitrates are at 10ppm