Users report losing noticeable volume with small filters on 1-3 ml batches and discuss switching between 4 mm and 13 mm filters depending on total liquid. Several describe air-purging or BAC-purging the filter afterward to push retained liquid into the vial. Opinions differ on whether volume or pressure is the main risk for tearing a 4 mm membrane and on the best filter diameter for a given batch size.
What this discussion establisheswhether 4 mm filters should be limited to under 1 ml or can safely handle up to 3 ml with slow steady pressure
Still openexact normal loss percentage for a .22 micron PES filter on 1.5 ml
Nothing here is advice.
I'm wondering what amount of loss counts as typical when filtering solutions. On my first try with the fine-pore PES version it felt like the full 1.5 ml just disappeared. Could the whole step be nothing more than a trick to make me lose my peps?
There are a few videos that show this. They add roughly 15 units of BAC in a separate syringe and push it through into the already filtered vial.
I suspect the four millimeter filter might cause me to drop roughly three to five units.
I ran into the membrane giving way when trying to push volumes past a single milliliter using the small diameter version. From what I gathered that amount often causes it to fail unless the flow stays extremely gradual.
I've heard/read the same.
I figure the issue comes more from uneven pressure than sheer quantity. When I push on the plunger while going through the process, that effort gets spread thinner over bigger areas. So with a small 4mm one, it's simple to push too hard and damage the thin layer.
For volumes of three milliliters or less I pick the four millimeter filters but switch to the thirteen millimeter ones once the amount goes higher. Air clears out the smaller filters while BAC clears the larger ones to deal with liquid that stays behind. The smaller size leaves behind roughly two to four IU whereas the larger leaves seven to ten IU and that changes with who made them.
That's the reason behind my earlier remark about taking it slow with the tiny filter. Those small ones only suit quantities below a single milliliter, while the larger size works for amounts from one to ten milliliters.
Using that needle size ends up discarding too much of the substance with smaller volumes. Folks see this differently, yet my aim is keeping the highest amount possible inside the container. Maintaining even force at one or two pounds works without problems.
Personally what stands out to me is the milligrams of peptides moving through the filter. Bacteriostatic water does not create the blockage instead it comes from the impurities one wants to separate out.
My choice depends on the volume of the mixture. The larger quantity of powder looks identical to the smaller one once prepared. I add either five hundred micrograms or one milliliter of the water, but the filter I use stays the same four millimeters in both instances.
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