Thoughts on over skimming

[mr.wilson]

Use whatever phyto you can find that isn't overloaded with heavy metals, or trace elements as we call them.

The nightly PH drop is hard on certain corals like xenia and most SPS, but not so much with LPS. You could have secondary metabolites (allelopathy) stressing out the LPS. You will definitely have more once you shut down the skimmer.

I agree that adding a refugium just to regulate night PH drops isn't worth the negative aspects (tinted water, secondary metabolites, and further nutrient depletion). If your nutrient levels are already at zero, a refugium doesn't offer you much for the hassle. You could consider growing xenia or whatever grows best for you, in the sump on a reverse photoperiod. It would export heavy metals and pay for the extra food you will be adding

Running the skimmer at night will at least assure you are oxygenating the water as much as you can. My suggestion of shutting it off at night may not work so well in that respect.

What's you reasoning on not using carbon? Do you use any ion exchange resins or phosphate removers? You might want to reconsider carbon if you are cutting back on skimming to take care of secondary metabolites.

How is your salinity (sodium level specifically) with your balling system? You may have an ionic imbalance of some sort, but the fact that your issues are with LPS I would still guess it's a nutrition issue and not chemical. The amino acids may do the trick. If the problem persists you could take the plunge and try vitamin C (ascorbic acid) dosing.