need help with noisy pipes please

[lastlight]

Access is really tight in there. Be tough to do any cutting/mods at this point. I tried a few holes in the fuge drain and gave up when it did nothing. At this point have the outputs of each half above and below the sump surface and that seems to have stopped the periodic gurgling. Now i just hear minor splashing but it's still too noisy I think.

For the fuge i might hunt around for a 1" valve and make it herbie. For the water change tank I only have the 1 drain. Poor planning on my part but I assumed it'd be safe since that tank only gets filtered water. Hmmm...