Umm... I think it's the cheapo bulbs...

Couple of things-

Digi ballasts are infamous for difficulty dealing with less than pristine power supplies. Don't know what your power is like, but anything at all flaky ( imperfect extension cords, blackouts, brownouts, motor surge on the circuit) will cause them to misbehave.

" Digital Greenhouse" is not a reputable name- I don't know a thing about them, but I'd wager that it's Chinese manufacture. Not exactly known for QC.

"GrowBright" bulbs seem to be exclusively marketed by HTG- Again, an unknown name, sketchy sourcing, prob Chinese manufacture...


I'm afraid that you got what you paid for...

But you could try putting a decent bulb in and see how long it lasts- Ya might get enough out of it to pay for a decent magnetic ballast from a reputable vendor, purchased locally.

Cheapo gear is like Walmart tools- Ya just end up buying them again and again, and it costs more over time than just spending the cash right up front.

Ask anybody who uses Hanna meters