Have been using mild dishwashing detergent to do the drastardly act for more than 10 yeara now.
Just be sure to do a lot of thorough rinsing with fast running water for at least 45 sec to remove dishwashing detergent residue(s) before drying, but please don't do this with sandwiched/ multi-element filters as chemicals and moisture may be trapped in between layers.
i feel whether cheapo or not, i don't think there's the need to wash them under running water. use lens cleaning solution should be more than enough. Running them under water may (most likely WILL) trap water between the rim and glass (it's called capillary action) and for it to dry up naturally may take up to days or months, unless you want sun them, but without g'tee that it'll work. So you'll risk having a moisture releaser on the front of your lens. Promoting fungal growth.
Well, if they'r dat cheapo.. throw them away!! hahaa.. wad's the point of washing the filters with detergent and damage the coating?? Might as well throw them away rite? If want to clean and use them, use the lenspen is much faster and cleaner.. =)
Lenspen cost about $10 at most major camera shops. :thumbsup:
if you absolutely must wash your filter, use a wetting agent (ilford makes it). It is essentially similar to detergent although ilford claims you can use it for filters and lens. It works for my filters when i do bother to clean them (hardly). Never washed a lens before! On the other hand, just buy a new filter lah. If u use a SMC one, washing will prob affect the coating.