Help! oncidium roots with black spots...

[Zekeyflower]

I don't use fertilizer at all and I usually water about once a week with tap water. Perhaps it's something in my tap water that's affecting the roots. Any suggestions for bark brand? I was using some stuff that I got from Lowes and it was a larger bark that tended to dry out quickly- that's why I tried to mix in the moss. I've had this plant for over two years now and although it grows bulbs, it never flowers so I'm definitely doing something wrong. I think it comes down to the watering because the bulbs always wrinkle so that indicates not watering enough BUT then when I put in moss I get fungus gnats and leaves start turning yellow.... So yea I'm switching back to bark and watering more. Also, any idea why the leaves began to yellow? I cut the yellow tips off and sealed with some cinnamon and when I unpotted the plant I sprayed down the roots with hydrogen peroxide - left it to dry out all night and this morning the roots look less scary.

[Zekeyflower]

Oh and side note- one of my bulbs is connected to the rest literally by one root lol but I'm too scared to separate it. Maybe down the line if I can ever get this plant happy!!!

[YetAnotherOrchidNut]

You gotta fertilize. Bark has almost nothing in terms of nutrients. The rule of thumb is water weakly weekly. That is, water at very low strength fertilizer (compared to the typical for non-specialist orchid fertilizer), 3 weeks out 4, then on the 4th flush it big time with unfertilized water. Ideally get yourself a quality brand of organic/bio liquid orchid fertilizer online. Follow the instructions. If its good quality they will include instructions for weekly watering. Flush your roots regularly with LOTS of tap water. Use finer bark to increase the surface area that gets wet without introducing stuff like sphagnum. You can also use perlite to increase water retention without attracting gnats.

But seriously, you gotta fertilize. Your yellowing leaves and no flowers are likely directly because the plant is not getting the nutrients it needs. I mean think about what would happen if you lived off of bread and water for 6 months, you would get all kinds of nutrient deficiency diseases. Your orchid looks surprising healthy to me given you aren't fertilizing, but it is probably sacrificing old growth to produce new growth, hence the yellowing leaves. And since it doesnt have the raw materials it cant construct a flower, and for all we know it isnt getting the minerals it needs so the roots aren't as healthy as they should be.