It’s totally understandable if you have a few questions about dosing the PNS (purple non-sulfur) bacteria-based products PNS ProBio, PNS Substrate Sauce and PNS YelloSno. For one, they’re all unusual products and it’s likely that you haven’t worked with anything like them before. Also, as with any food or live product, ideal dosage varies from tank to tank.
Here are a few important things to consider as you go forward. First, you can relax, as both they’re all quite safe and aren’t easily overdosed. Second, it’s good to keep in mind that YelloSno is simply a food and not alive, whereas ProBio and Substrate Sauce are very much alive; YelloSno must be refrigerated (especially after opening) whereas ProBio and Substrate Sauce should be stored at room temp.
The dosage for ProBio and Substrate Sauce is 1.25 ml/gallon whereas YelloSno is 1.0 ml/gal. Each product may be used as often as daily (less often is acceptable, depending upon results and your goals). They may be used together (even mixed together) and used at the same time. However, with ProBio and YelloSno (as with the PNS Product Combo), many users find an alternating schedule to be very effective (that is, dosing just one product each day, switching between the two from day to day).
These products are easily dosed by hand. Dispensing YelloSno from an automatic dosing devise is possible. However, to prevent contamination, the product must be well-chilled. Also, it should be on a stirrer to keep the “snow” well-suspended. Dispensing ProBio and/or Substrate Sauce from a doser is also possible but may require frequent cleaning due to potential clogs (live microbes can form a biofilm over the tubing’s inner surfaces). As an alternative, particularly when seeding a system to establish permanent colonies of these bacteria, one might add the first dose to a porous biomedium (filter sponge, ceramic block, etc.) and just chuck that into some area of slow water flow in the sump/refugium. For use as a probiotic, ProBio and Substrate Sauce may be soaked into any aquarium food a minute or two prior to feeding; this can increase feed conversion and reduce waste production as well as introduce healthful carotenoids into your fishes' diets.