I didn't see on my phone last night, but on my main computer this morning, I checked and expanded a section on that link and got some dosage information. From what I can tell, the label instructions are for 30 ppm, a bit high, but then, they dose only every 3 days which is odd. They also say don't dose with salt, which is really odd.Well, you will be on your own to some extent here, since I don't have a dose from the bottle to use.
Formalin is typically dosed from Brooklynella at 25 ppm. This works out to be 0.9 ml per ten gallons. That is for 100% formalin. If your product is truly just 30% formalin, then you would adjust the dose to 3 ml per ten gallons, but I cannot guarantee that is correct since I don't actually know what's in the product other than it says "30% formalin".
Jay
Jay