LK will stain your roots brown, but it isn't going to kill your plant (as long as you use it right).

Hygrozyme will leave no residue or "gunk" on your roots and won't even stain them. Again, unless you are overdosing your plants, it is IMPOSSIBLE for either of these products to kill your plants, they are meant to convert dead plant material into usable or inert matter and provide a healthy, beneficial environment for your plants.

MJMonkey...if both of those products killed your plants in your "limited experience" i would have to say it's grower error and not the fine products you don't know how to use.

I've used hygrozyme forever and it has made life much easier and never killed a plant. 4-6 ml per gallon. I've cured 3 cases of root rot with it. I will sing it's praise for all eternity.

We need much more info to know what's going on. Clear translucent slime sounds like the beginning of algae or the suffocation of your roots.

I'm going to assume you are in DWC...Is your Res light proof? any speck of light will encourage ample algae growth.

Is your res too warm? if it's over 75 degrees Fahrenheit you are creating perfect conditions for bad bacteria and other pathogens to attack and suffocate your roots.

Do you have PLENTY of oxygen in your res? Cool water holds more dissolved oxygen than warm water. Get your temps down, add an airstone or two.

It's quite possibly too late for your plants if the roots are already suffocated and dead.

Wrap/paint your res with black to block light, paint/cover the top with white to reflect light back up and keep temps down. put a fan near the res to move air around it.

keep us posted, good luck

peace.
Skeet.