I've noticed that some PB posters utilize lake dyes in their ponds. Some folks use lake dyes to help reduce weeds/algae through sunlight reduction while others use them to simply enhance aesthetics.
I won't go into the pros and cons of using lake dyes in ponds being managed for fishing. However, generally speaking, lake dyes (used at levels needed to inhibit sunlight penetration) can be detrimental to phytoplankton production and will therefore have a negative impact on the "natural" food chain. That impact can be offset to some degree with a fish-feeding program. But, that discussion and debate is not the purpose of my post.
Instead, I simply wanted to offer some advice (or "public service announcement") to those who elect to use lake dyes - for whatever reason - after fully understanding the associated pros and cons.
I've noticed a significant increase in the number of lake dye producers over the past few years. Even so, there are only two lake dye brands that are registered with the EPA for weed and/or algae control: AQUASHADE and ADMIRAL. All of the other lake dyes make no pesticidal claims (or do so very subtly) and are therefore not obligated to obtain an EPA registration.
HOWEVER, strangely enough, the knock-off "generic" brands always seem to list the identical use-rate recommendation for their product as is listed for the EPA-registered brands (ie. 1 gal. per 4 acre-feet). Also, the non-registered products always APPEAR to cost sigificantly less than the registered products. So, it would seem rational for most folks to say "Hey, this no-name brand lists the same use-rate as AQUASHADE and ADMIRAL - but it is a lot cheaper. I think I'll just use it and save some bucks".
If this is "you", then you've probably just bought into a cleaver marketing tactic.
Case in point: When purchasing a lake dye, you are NOT buying a GALLON of dye. Instead, you are actually buying powdered pigment [usually acid-blue 9, and sometimes acid-blue 9 + acid-yellow 23] that has been formulated into a gallon of liquid that is usually packaged in a 1-gallon jug.
Now comes the tricky part. Different lake dye formulators use different types of analysis to indicate their product's "pure dye content" (PDC) - which is the only accurate means of determining the dye-concentration of any lake dye product. Many of the knock-off lake-dye formulators don't even indicate their product's PDC, since they're not required to do so unless they actually register their product with the EPA. Why do they not list their PDCs? Easy, because their PDC is usually a lot lower than the more expensive lake-dye formulations. Even so, they attempt what I consider "deception" by listing a recommended use-rate that is identical to the EPA registered lake dyes.
All this to basically say: Don't be fooled into comparing the cost-per-gallon of two or more lake dyes from different manufacturers. Just because the various products are packaged in 1-gal. containers and list the identical use-rates does NOT mean that they all contain the same level of PDC. In fact, it is comical how much the PDC's differ amongst the various lake-dyes on the market these days.
So, if you're using one of the cheaper knock-off lake dyes (which are virtually guaranteed to contain NO acid-yellow 23) and wondering why you have to use so much to get blue water OR why you have to retreat so frequently, now you know. There are many differences between lake-dyes - besides their price tags.
