bio slime

[floridaboy]

I work for a newspaper. Our film processors accumulate a clear emulsion gel in the rinse water tank. Over a few days it develops an algae type of build up all over the tank. We treat it with mild bleach, however the bleach and photo development fixer vapors combine and cause corrosion on the stainless steel housings. The question finally is how can we control this bio slime? Is there another non-corrosive chemical agent we can use or would hot water be of any use?

 

[mmenarry]

There are commercially available biocides that you could use which should be less corrosive. They are used in cooling towers and the like.
Michael

 

[ivanlocke]

A strong UV light left over the tank every once in a while might work as well.

 

[floridaboy]

Are there any biocides that are recommended - Brand name or chemical type?

 

[ajw160]

Floridaboy:

Try some non-oxidizing biocides: Glutaraldehyde or maybe Isothiazolin (active names).

Both of these are extremely effective at penetrating and killing because they are cell de-stabilizers and not oxidizers (therefore are nicer to metals). However, because of that nature the kill time is slower than an oxidizer like bleach, if that's important. Bleach by itself will corrode low grade stainless.

Contact a local industrial water treatment company and ask for products that have either of those actives.

Note: Glut. is expensive. Iso. is extremely dangerous to come-in-contact with. The danger with Iso. is that it's a common skin-sensitizer that in concentrated form will make you break out in a really nasty rash, from then on you'll be extremely sensitive to any exposure and it's in nearly everything except Ivory soap and baby shampoo; check your labels.

 

[floridaboy]

After much research, we found that the bio-slime is acually leftover pure Gelatin that is used to suspend silver halide crystals in photographic film. It is normally not an issue in the developing tanks because the temp is at 95 degrees. But when it reaches the wash tank the Gelatin starts to solidify in the 75 degree water. What happens to Gelatin when it cools? Gels up. What we are going to try here is heating the water to 85 or 90 degrees so the Gelatin will not be able to turn solid and hopefully not allowing for anything to adhear to it or form on it.(ie. algea)