Spindle water question...

[CharliesWoodStuff]

I've got a water cooled spindle that I bought with my HD4. Rather than depend on the $5 POS Chinese pump, I bought a CW-3000 Chiller off Amazon. Just installed it and appears to be working well. However, the water bucket I previously used was moldy / slimy when I took it out from under the table. Other than replacing the water monthly, how do I keep the water from getting slimy? Can I add bleach or something to it? Will that damage the internals of the chiller or the spindle? Thanks!
Cross posting for a wider set of eyes...

[T&K Woodworks]

We always add 1/4 cup of bleach to about 4 gallons of distilled water. We’ve had our machine over a year and a half and no problems so far.

[gordread]

Distilled water should not get slimy. If you add a touch of bleach it probably wouldn't hurt.