Product review (5 stars): So when all is said and done, this product still works the best.
I've been using this product for about five to six months of every heating season since I purchased my two-tank Vornado Evaporative Humidifier with two wick filters approx 10 years ago after another type died within the first few weeks of use.  In that time I have never had any unpleasant odors or sign of algae or mold while using it.  I also use a Holmes water treatment product to control mineral buildup.

I did try a product from BestAir for its claims to also control mineral buildup on the wick filters.  Unfortunately, it made my humidifier maintenance chores worse instead of better---I went through much more vinegar dissolving the hard yellowish-buildup than I usually do.

As for measuring & dispensing, since the cap on this Original BT Humidifier Bacteriostatic Water Treatment has been made sooo very much smaller, and the cap on the Holmes product I bought in bulk years ago is also very small, this year I've been dispensing them using one of these droppers&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/katito-White-3ML-Disposable-Plastic-Eye-Dropper-Set-Transfer-Graduated-Pipettes-20-PCS/dp/B00P7QZDK4/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">katito White 3ML Disposable Plastic Eye Dropper Set Transfer Graduated Pipettes (20 PCS)</a>, after I measured how many of each it would take for the requisite amount in each 2.1 gallon tank, and this has been the best year so far for mineral buildup.

The warnings on some of the other products really do give one pause, but I'll probably never forget the few months last winter that I tried what proved to be more-odoriferous-than-I-can-stand tea tree oil instead of this product since I'm reminded at the kitchen sink every time the odor floats out of the empty tanks during refilling.  So I suppose it has permanently embedded itself in the tanks' plastic.

So when all is said and done, this product still works the best.