Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I know some people are allergic to blood worms, and if you feed the blood worms, then work the tank you can get a reaction.
If your arm was hurting, what about the fish? They were breathing that stuff!
If you found it was only when the mulm was in the water I would do this:
Get some high gloves. These are available as disposable, used by vets who do large animal work, or sturdier material, sold for marine tanks with sharp coral.
Vacuum the substrate more thoroughly every week, perhaps 1/4 of the tank each time in rotation until the mulm is greatly reduced. Then maintain it that way perhaps once a month deep vacuum all exposed places.
If you know you will be tearing into the tank that way again, drain most of the water and move the fish. Can't be good for the fish, having that crud in their gills. When you refill put a plate or plastic bag over the substrate and pour the water in slowly to minimize the clouding.
If you are just working part of the tank, I would still drain 1/2 the water, anyway, and use the gloves. Then refill and do a water change if the water is not very clear.
I prefer the disposable gloves. They are finer, and allow better feel for what I am doing. I also have the heavier gloves, and find they are too thick to allow a good touch. I use the disposable gloves that you can get at most stores. They are only wrist-high, so I do need to drain the tank if I need to use those gloves. Mostly I do not use gloves.