agree with above 2 inches below net pot and roots will grow looking for the water,also the bubbles bursting will provide enough water until roots are sitting in water.
certainly wouldnt pay that for one,as you could use big clear plastic bottle with lid end cut off for next to nothing,but u got as present so cool,good luck.
youl need to keep an eye on temps in the bucket,is the clones rooted yet???and clones dont need much light,if you want to create humidity put each one in a clear food bag and tie or seal,thats it.
agree with above either go hydrogaurd or h2o2,either way.Its probably been the high temps of water thats done it!!get the roots sorted first and water temps,then see if spotted leaves get worse,and take it from there.
dont strip leaves for the sake of a couple of spots,leave them on and try and fix problem,if you dont fix problem then its just going to happen to other leaves then youl want to strip them off too.