Diatomaceous Earth Sap Filter

[Russ]

I've been hearing more about the use of diatomaceous earth filters for clarifying cloudy sap prior to cooking. I've looked around for more detailed info, but can't find a good source for a food-safe filter canister. Better yet, anyone have plans for a DIY diatomeaceous earth filter canister? Any good/bad/ugly stories about this sap filtering technique?

Thanks

[Maple Hill Sugarhouse]

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[gearpump]

I did a little research on this idea a year ago and found out from other producers that a DE filter is hard to clean out and over the course of a season the bacteria will build up in the filter media and cause more dark syrup towards the end of the season. The easyer solution I found was to get a case of 5 micron absolute bag filters. They are like the ones in the maple catalogs, but filter out much finer particles. After week you just replace the filter with a new one and start fresh. I think the industy size is a # 1 bag size, 16 1/2"x 7"O.D.

Marty

[mapleman3]

Probably not a good idea to take your pool filter down and stick sap through it then use in the summer to swim again :mrgreen: :wink:
they do advertise them though I think the DE is the same as for filtering syrup(food Grade) not the pool quality stuff....

[Russ]

Mapleman, I agree...

It sounds as though I will be all right with a (used/inexpensive) DE pool filter, and use food-grade DE in it. Pool-grade DE has a high silica content; food-grade has no or minimal silica content (based on what I read).

I like the filter bag idea. Marty, where did you get your bags and how much were they?

[gearpump]

I got my filter bags thru MSC Industrial Supply at work. I think they only cost $3.00 a bag if you got a box of 20. They fit the same pop-on adapter heads sold at the Maple Dealers. At this low cost I changed them after a week or less depending on how they smelled. You nose can tell when they get that yeasty stink from bacteria! I had no problems with flow rates of the 5 micron filters even with feeding it with a 2" hose and gas pump. I also noticed in the lastest issue of maple digest they had a page on sap filters. The best ones were the 5 micron cyl./cloth,cartridge filter, and DE filter. The bag filter was only 50-100 microns and did not do so good. I wonder how different a 5 micron bag filter would have done. These are by far the least expensive and offer the same if not better filter advantages of the cloth and cartridge filters.

Marty

[Russ]

Thanks Marty, I found them at the website of the company you mentioned. How well do they clarify your sap, especially if it has gotten cloudy after a day or two of storage?

We already use bag filters (that someone gave us) when we pump from our ground tank to the overhead tank, but those are likely 100 micron bags. If we could fit a 5 or 1 micron bag over the top of that bag, we would get out the bigger stuff before it got to the finer filter. I don't want to mess with DE if I don't have to.

I also noticed that the polyester bag filters are FDA food safe. Thanks again.

[Maple Hill Sugarhouse]

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[lew]

In the past I have used a D.E. filter to clear up cloudy sap. I wasn't comfortable putting the filter in line in front of my RO machine, incase any of the DE got past my sock filters of 5 micron cartridge filters, they migh plug my membranes irreapairably(I think I spelled that right). So I layed out 4 - 400 gallon stock tanks so that my sap truck could dump into them easily and I could filter each tank to the best of my ability, suck it back up in the truck and put it into the main storage tank. Alot of extra handling, especially to make grade B syrup, but we have a large market for B and it was a short year. Any way, The DE filter did an amazing job. We put nasty, cloudy, yellow, tip over the tank sap and cleared it up to almost sparkling. The only reason I can't call it sparkling is because it still had its yellow color. With no cloud to the sap it fed through the RO beautifully. We have older Coster RO's with piston pumps which are quite noisy. When you try and put cloudy sap theough them the pressure rises and they get really loud. With the DE treated sap, It was like running first run sap. There are only two draw backs I can see. One is controlling the DE that does get by the filter. Each time I tried this, there was a small amount of DE on the bottom of each tank. We were careful to avoid as much as possible when "regathering" the tanks. My membranes are too expensive to toy with. The other problem I see producers having, is being too cheap. Now I'm as cheap as they come, but you can't expect to filter sap today with the same DE you used yesterday, even if your pressure hasn't built up enough to warrant changing it. When you filter with DE, you are filtering down to around 1 micron (if my memory serves me correctly). You are keeping an awful lot of bacteria, yeasts, and molds in that media. It is an excellent medium for these organisms to grow in. If you put halfway decent sap through this bacterial nirvana, you're just asking for problems. Even though you can't see the cloudiness created by the bacteria, they are still present in the sap and the filter. Therefor you need to clean the filter out when done processing your sap and you must sterilize your sap as soon as your done filtering it, either with an Ultraviolet light or boiling it. The syrup we made from this sap was of good to excellent flavor, well worth the effort. By doing this, we were able to extend our sugaing season by a couple of short runs that would have otherwise gone on the ground. Now that we have shrunk our operation, I am acquiring a smaller DE filter to pu in line between my sap truck and storage tank. I think it will definitely help with the longevity of my RO membrane life(the cleaner the better) and improve flavor by not boiling that bacterial cloud. Sorry this got so long winded, but I thought this experience would be helpful.

[Parker]

very helpful

[Parker]

Do you pump the sap through this DE filter or run it through with just gravity,,,,If I ran my sap through one of these filters then directly into the evaporator do you think the traces of DE would burn on the pans,,build up in the evaporator,,,or stay suspended in the sap-syrup through the whole process eventually be filterd out in the filterpress? how big (flow rate) is the filter you use?? thanks in advance

[lew]

The sap is pumped through the filter, not gravity. The traces of DE that do end up going through the filter end up settling out fairly quickly and can be seen on the bottom of the tank. I don't think very much would end up in the evaporator, and if it did, it would removed by the filterpress. As far as burning to, or sticking to the pan, I have no clue. I don't think it would adhere, but am not sure. As far as how much DE actually gets through the filter is a matter of how "tight" the filter is. I know 3 pool owners who run DE filters and they all have said that they get a small amount of DE discharged back into their pools when then recharge the filter. It dosn't create a problem for them though. They just run the filter and the discharged DE settles out (even while the pool water is in motion) and then they vacuum it up and the filter catches it.

[brookledge]

It seems like you could run the first sap out of the filter back into the unfiltered sap and that may eliminate the sediment that comes out when you change the DE. Maybe that won't work.
I know when I use my filter press I always run the first few seconds back into the unfiltered syrup so that it is good and clean.
I know one of the retailers near buy that had a list of things that the DE filter would take out. The list refered to everything by microns. Bacteria and yeast are definately filtered out with a DE,that is why cloudy sap will come out clear.
As Lew said it is probably key to changing the DE on a regular basis so that the bacteria does not grow in the filter.
I'll see if I can get a copy of the paper that listed everything and its micron size.
Keith

[Russ]

Based on Lew's excellent summary, my next question is: where is the best place to get the DE filter cannister? Will a regular pool DE filter work? Any "homemade" alternatives?

[lew]

Any of the DE filters I have seen in the manufacturers catalogs appear to be for pools. The one that i used was designed for pools and worked great. I don't know of any homemade alternatives, but where there is a will, there is a way. The biggest problem I can see is "catching" the DE on a porous surface, so that it can filter. If you keep your eyes open, you can buy a used one for under $100. I bought mine for $50. A lot cheaper than buying a new one, several hundred dollars.