I partially agree with balor that there can be too much of any good thing including probiotics. The good news is that the amount (for me, I know that's n=1) is quite a lot and you definitely know when you've had enough. I drank 4-6 cups per day of water kefir for around 4 months and it really healed my gut but right around the time I could finally handle an occasional dose of grain without symptoms I suddenly lost my appetite for large quantities of the water kefir.
I now drink either 1-2 cups per day or 2-3 cups every other day. That's worked fine. As long as it tastes fabulous to me I drink it; if I don't want it on a given day or notice it seems less tasty then I skip for at least a day. Since it isn't artificially formulated for palatability, it seems you just need to pay attention to your reactions and all is fine.
Are you dairy free? My other major probiotic is yogurt. I bought an heirloom Bulgarian culture and I make it using 3 parts whole milk to 1 part heavy cream. I love it! It has a wonderful flavor and is amazingly thick even though it lacks the "thickeners, stabilizers and preservatives" in commercial yogurt. I eat about 1/2-2/3 cup of yogurt every other day.
I also like pickles, olives and occasional sauerkraut.