Have you ever heard of someone using sodium silicate?ok, those are 2 TOTALLY different things. hopefully the guy at the store didn't give you the silicate as a substitute for hydroguard!
potassium silicate is a nutrient of sorts. It will help build stronger roots, but it's main function is to basically to strengthen cell walls....it puts 'concrete' in your stems, branches, and leaves making them a lot stronger, and also more resistant to pests (eg, leaf eating pests don't like 'hard to chew' leaves due to the silicate). I use silicate all through veg and the first 3 weeks of flower until all vertical growth stops. certain brands contain more silicate than others. I've used botanicare silica blast which was good, but have been using dyna-gro protekt which has a higher silica concentration....more bang for the buck. **silica is very alkaline, it will make your ph spike, so ph test after adding all nutes. always add first to your plain res water before adding any other nutes. If you must add it to a res already containing a nute solution, dilute the silica in water first before adding to the res. it will add to your ppm, but I use 2ml per gal of the protekt and it only adds 50-80ppm.
hydroguard is a beneficial bacteria. it is dwc success in a bottle. It contains a dominant bacteria culture that colonize your roots zone and basically kills off anything else that competes for food. They will help break down food for your roots and help nutrient uptake. I've run my rdwc system res as high as 77F (optimal should be 68F-70F) with no root rot issues...although the roots deffo like the res a bit colder. anything else in the bottle is inert liquid....nothing in this bottle will add to you ppm. If you are located in north America you can order off of Amazon. if in the UK, try Botanicare Hydroguard - One Stop Grow Shop Hydroponics
if you are going to do DWC, ppm and ph are very important. here are some useful reading and guides
beneficial bacteria
Some interesting reading on bennies in an rdwc system
ppm website - tells you which nutrient brands use what ppm scale
CF, EC, PPM 500, PPM 700, TDS… What’s the difference? | The Good Earth Organics Supply
All I do is hydroponics, mainly DWC, so if you have any questions just shout.
IslandGrower420
and you are one of the most helpful members of 420 too. thanks for being around mate.
