Speaking generally, that is, not directly to your water situation and not having seen your rack, I’ve used a number of isolation types from eBay cheapie foam blocks to SVS elastomer subwoofer feet, Stillpoints, Isoacoustics Iso-Pucks and Gaias, and more. Easily the best I've come across on the relatively lower end of the price range are the AV Roomservice Equipment Vibration Protectors (EVP 2” block style). They go for $135/3 and there are sometimes discounts for new and returning customers (not posted on the site). At the suggestion of its developer, Norman Varney, I got three High Density ones for under a low weight preamp on the bottom shelf and four low density for under an Oppo 203 on the middle shelf. I was impressed enough with the results that I ordered 6 more HD for under a dac and the preamp’s PSU. However, before putting them there I decided to try them under my 68 lb ATC active floorstanders, where I’ve had Gaia IIIs for some time (medium berber carpet over wood/concrete, hence sensitive). Varney says the place to start and greatest impact is with speakers, but I was very skeptical, given the degree of improvement the Gaias had made for me and many others, including pro reviewers and Paul McGowen of PS Audio. Well, I was shocked at the difference the EVPs made. Take long, fast piano runs, which are a good test of clarity and articulation. With the Gaias, piano runs were often a little smudged in part, but with the EVPs I could/can hear every note bottom to top. Extrapolate that out to other instruments, orchestras and singers, and it’s very big deal.
I will qualify this by saying that inserting the EVPs changed — elevated a little — the lovely tone and pitch I had worked hard to find with the Gaias, and not for the better re my tastes (although I know many people would have been wholly satisfied with the result). Changing one thing often either changes system synergy or exposes a weakness elsewhere. In my case, changing the preamp’s rectifier tube to something warmer and with a better bass restored the kind of sound I like and can listen to for hours. So I would suggest the EVPs are definitely worth an audition if your rack and floor allow.