Fluctuations will cause BBA typically. Depends on low-high light you have. DIY for a 46g you need either 2 yeast setups or a super efficient method to dissolve it. If you have the money, invest in a good Pressurized system. I had the same mentality that i can get away with DIY and I did, but i had EZ plants + low-medium light. When i moved to higher light and more difficult plants, i realized DIY was too unstable. Unless you are as experienced as Tom Barr, growing more demanding plants with DIY CO2 is a bit more tricky.
Like i said earlier, if you have the money and are genuinely interested in this plant hobby, find a good quality regulator, solenoid, needle valve, and seriously invest in it. Good quality regulators will last you a lifetime. Well, i can't say that for sure but the precision cannot be beaten by DIY.
I have 2 T-5 HO (39 watts each) and 1 T-8 SO (30 watts) on my tank. The substrate is eco complete. I know that DIY won't be as good as pressurized but iam a student and i'm low on cash (saving up for college and stuff
). Will DIY work if I just want a cheaper solution to grow my plants?