Yeah I would cover the whole bag block out any light. Algae is easy to get on hydroton, in DWC I would always use covers to keep any light out of my hydroton.I have been growing in soil and wanted to try grow bags with hydroton and hand feeding them until i get my aero system finished that im slowly building. My question is would you ave to cover the top of the grow bag so light doesnt get in or would it not matter.
Hand feeding in hydroton is going to get old quick.
Top watering would definitely get you algae.
Winner winner Sheen Dinner!+1 the top layer of hydroton shouldn't see any water or light for that matter.
Like you I have never had a huge algae problem I saw some green algae forming on top of my rapid rooter plug and I clipped it off after that I figured I'd cover my net cups as a precaution. I doubt a little algae hurts but that stuff is good at spreading so be careful. you can buy light blockers at the grow store or use Styrofoam cups, plates, bowls etc to cut out a hole the size of your net pot.I've never covered my hydrotons and never have had a problem. Sometimes a small amount of algae has formed but not to any ill effects. Or maybe I've never yielded as much as I could have? lol. Would a little algae hurt the crop?