This looks like the same just with different label. I use up to 1,0g per 100l as an initial shock (my is 65% calcium hypo) before I add nutrients. This keeps the water crystal clear for one week, than the solution is gone. Refill with fresh water, shock, nutrients, pH, feed, gone, refill, shock and so on. Water is circulating in reservoir and getting straight hit by the lights.
Things I have noticed:
If you have nutrients already in your water (especially high dose of sulphur) and you add granular HTH, it can precipiate and form gypsum. I think this can be avoided by diluting HTH in small amount of water and than just poured inside. Never tried that because its one step more, which can be avoided just with the change of the order of mixing. Its kinda making your own bleach and than dosing it as liquid. This might be the way for you since for measuring HTH you need some fine scale to be exact. 1,0g is the high end dose for already nicely rooted plants, this dose sooner on may restrict root growth. I would suggest to start somewhere 0,4-0,5 per 100l to see if it is enough for your needs. Those days when the water is cold, it takes longer time to dissolve, but its not such a big deal, since during that time you also get the temperature up to where you need it. When there is hot the shock does not keep it clear for the whole week only like 5 days, thats the time I use peroxide or just let the rest run through the plants and mix a new res. I am getting lazy so less labour is always welcome in my case. When I look back, that peroxide is kinda shit stuff, IMo only good for treating root rot, which is not a thing in coco, unless you have gnats, where the peroxide also do a big nothing against them. Its a good mouthwash but thats all.