Why are my pre-filters turning pink?

[letmgo]

Just bought a small RO this year and have noticed the last few days my flat pre-filters are turning pink in the middle where the syrup runs through. Does this have something to do with the RO?

[buckeye gold]

To me it sounds like bacteria growing. I have on occasion seen this in buckets after a warm spell. I pull the bucket and bleach it if I see that. I would toss a filter I saw that in, prefilters are wayyyyyy cheaper than syrup!

[letmgo]

I don't think it is bacteria, as these were brand new pre-filters that were white when I used them, and were pink when I washed them out--all over the span of an hour.

[buckeye gold]

Hmmmm probably not bacteria then. Maybe someone has an answer

[psparr]

Is the felt filter turning as well? I know they can take on some color.

[letmgo]

The felt is getting a slight pink hue also.

[psparr]

Could just be the staining from the syrup. Usually more brown, but if your syrups reddish, that could be it.

[Pauly V]

Mine are doing the same. No ro. Medium Amber syrup.

[mapleleaf]

new pre filters from leader in swanton vt mine turning pink also ?????

[CampHamp]

Red leather stove gloves (Harbor Freight) will leach onto a wet filter.

[lew]

Back when we used to use flat filters on certain years the prefilter would turn pink, not every year though. And some years Pinker than others. Definitely not bacteria, maybe a specific mineral or something that came out of the sap that year.

[letmgo]

These are new pre-filters I just bought from Leader.

[Pauly V]

Red leather stove gloves (Harbor Freight) will leach onto a wet filter.

no gloves..just flesh burns..

[RollinsOrchards]

Could it be the cleaner you are using? One of the acid/sanitizers we have used on Dairy equipment turns stuff pink.

[TheMapleNews]

A couple people have mentioned this problem and the folks at the Proctor Center brought it up last week during the Maple Schools in Vermont. Anyone had this problem? Filter papers turning pink?

[DRoseum]

How are you cleaning them? Are you reverse rinsing them, boiling them out in a pot?

I have seen them turn pinkish after using, reverse rinsing with hot water and drying without boiling them. Not sure but might be residual niter/sugar that causes it.

[tcross]

sometimes mine do turn pinkish.... sometimes they don't. i have zero idea why that is! they usually turn after using them a few different times. no R.O and make all the different grades. i also have a mixture of sugar and soft red maples. i've only ever used the leader and LaPierre prefilters. i don't recall the LaPierre filters turning pink, but they are made of a totally different material than the leaders. i prefer the leader pre filters!

[DrTimPerkins]

For several years the filter papers on our press have sometimes turned light pink after filtering syrup. We aren't sure why.

What has been more noticeable is the RO wash water turning anywhere from a slight pink to a brownish-red to a near-black color. The darker the color the harder it is to wash. We and at least some equipment manufacturers attribute this to manganese and iron in the sap that is accumulating on the membrane, but there hasn't been a real in-depth investigation up to this point. When it is really noticeable it may require an acid-wash to restore membrane performance.