flying skull z7

so its Z9 here where i am but i bought it on a desperation after reading two maybe three threads. Before using this a lot of people started making me nervous as i read reviews and a lot of people said its terrible, basically a scam etc. I used it for the first time today at .25ml for about 6L of...

Anyone know if using Hydroguard with Flying Skull Z7 is beneficial? Currently running a 5 gallon bubble bucket dwc and just started using Hydroguard as well Flying Skull Z7 in my reservoir. Wondering if using both is beneficial or counter productive.