What are Water-Absorbent Polymers and how do I use them?

Added by: snoofer

Contributed by: Snoozer

What are polymers and what are water-absorbent polymers?

A polymer is a string of repeating molecules that forms along chain. DNA is a polymer, as are starches, proteins, etc. Forexample, casein - the protein that makes cow's milk - is a polymer.About 30 years ago the plastics industry was looking to change thenegative image people have of the word plastics, and pick up on afriendly sounding name to confound the public so they started calling awide-range of their plastic products 'polymers'.

Water-absorbent polymers (also known as hydro-gel, watercrystals, super absorbent polymers, etc) - are simply a type of plasticthat possesses some unique water absorbing qualities.

What makes this polymer water absorbent is the presence of sodiumor potassium molecules that form bridges between the long hydrocarbonchains. These bridges - known as cross-linking - enable the polymer toform into a huge single super-molecule (desirable for a number ofreasons), including its ability to degrade in the environment andbreak-down into simpler molecules, and hold significant amounts ofwater. The polymer crystals that you purchase, whether the size issmall, medium, or large, will always be a single molecule (making itvery difficult for you to chop up large crystals into smaller crystals- try it in a coffee grinder sometime.)

All water-absorbent polymers are cross-linked, and cannot work ifthey are not cross-linked. It is often written on labels to make itsound like a "feature" - don't be tricked into paying more for polymersthat are labeled as being "cross-linked".

How are they used?

Water absorbent polymers (hereafter referred to as just polymers)can be used for two purposes: to store and hold water to add an extrafew days between watering; or alternatively, to protect your plantsfrom over-watering - especially if they are planted in an area thattends to pool water.

Are there different types of super-absorbent polymers?

There are about 800 to 1000 different recipes for these polymers -but they are divided into two big categories: polyarcylamide andpolyacrylate.

Polyacrylate (called in the industry PAC) are used in disposablediapers, sanitary napkins, etc. and are capable of holding a hugeamount of water - between 600 and 800 times its weight (purity of thewater determines this range - the more dissolved solids in the water,the less liquid the polymers can hold).

Polyacrylates are usually made with sodium and are moreenvironmentally friendly, breaking down first into ammonia salts andthen nitrogen and CO2 in about 4 to 6 months. They are often sold withan environmentally friendly green label and retail for around $10 to$12 per pound.

In contrast, polyacrylamides (often known as PAM) absorb only about300 - 400 times its own weight in water, use a variety of potassiummolecules for cross-linking, and take between 5 and 7 years tocompletely breakdown. Because of the lower absorbency and longer timeto breakdown, polyacrylamides usually sell for around $6 to $8 perpound.

Do polymers affect the taste?

Do water absorbing polymers affect the taste of finished marijuana?
I experimented with the use of polymers on my canola farm over aperiod of years, and have grown cannabis in extreme drought conditionsusing these crystals.

Growers have reported that these polymers adversely affect thetaste of the finished product. Many others have reported no impact onthe taste of the quality of the smoke. This debate and the differenceof opinion is due to the type of polymer used.

Polyacrylates will negatively impact the taste of cannabis. Asnoted, polyacrylates take approximately 4 to 6 months to completelybreak down - with intermediary chemicals including ammonia salts,nitrogen (nitrites), and CO2. This breakdown usually happens when mostgrowers are flushing their plants - and it is the plant absorbing thisresidue that negatively impacts the taste, including a variety ofsodium by-products.

In contrast users of polyacrylamides - which take 5 to 7 years tobreak down - will not be introducing intermediary residual chemicals totheir plants, and will not notice any impact on taste or quality of thesmoke.

Given a choice between the two - it is strongly recommended that growers use the less absorbent polyacrylamide.

How do I tell if the polymer is polyacrylate or polyacrylamide? (if there is no label)

If you cannot buy from a recommended online supplier, and arebuying locally, look for these four clues to distinguish products:absorbency, price, "environmental friendly", and a "safe for foodcrops" label.

Polyacrylates (the one you want to avoid), report absorbency of 600to 800 times its weight, cost around $12 Cdn per pound, and almostalways have on the label "Environmentally friendly".

In contrast, polyacrylamides are labeled as absorbing 300 - 400times its own weight, are priced at $6 - $8 Cdn per pound, and may havea note on its label that reads "Safe for Agriculture and Food Crops".Only certain polyacrylamides (and very few polyacrylates) can belabeled as safe for food crops.

Can you recommend a reliable source for polyacrylamides?

The web site is : Watersorb

This is a non-profit - native American run business. Their customerservice is absolutely great. This is a statement taken from their webpage: "WaterSorb.com is an American Indian owned and operatedcorporation dedicated to restoring and improving the environmentthrough technology, and meets all qualifications as a SBA 8 (a)minority owned corporation."

Their prices are the best you will find too - $12 for 2 pounds; $26for 5 lbs - delivered anywhere in the USA. They are very good people todeal with and understand your needs.

An international package - 4 lbs delivered to Canada or anywhere inthe world is available for $24.50 US from the same website - in theinternational section.

{Edit - changed international price to reflect recent shippingprice increase. The FAQ author has purchased from this company forseveral years and service is excellent. They also have a veryinformative web site that will provide additional information onpolymers.}

What size do I buy?

Avoid the powder, it is difficult to mix thoroughly. Likewise, thelarge size is also difficult to work with and to mix thoroughly withthe soil. Both tend to cause the roots to clump up and bind around thepolymers rather than grow outwards and search for water in the naturalsoil environment. Improper use of either of these sizes actuallydiminishes performance characteristics.

If you are growing indoor with a soil mix (perlite, etc), in finesandy soil, or where water pooling is a problem, use the small grade asan amendment.

If you are growing in heavy soil or in drought conditions use themedium size. Why? In sandy light or fast draining soils you are mostlikely using the polymer to slow the rate of water drainage and youwant to maximize the probability of water contacting the polymer andbeing absorbed.

In heavier soils and in drought conditions the medium grade isbetter for several reasons. One characteristic immediately noticeablewhen growing in drought affected areas is that the soil tends to hardenand compact. There are several reasons for this - earthworms and otherinsects are not living in the top couple feet of soil and do not workand loosen the soil; plants can't live naturally in drought, and theabsence of a good root system causes the soil to compact; and finally,the heat itself causes the soil to expand slightly and fill the gapsthat might have once existed.

Because the medium size polymers expand rapidly when they absorbwater and contract when they release the water to the plant orenvironment - this expansion and contraction helps work and loosen thesoil and promotes good root growth in what would otherwise be a verydifficult environment.

How much do I use?

Consider that one cup of dried polymers (250 ml) will absorb 100liters of water (about 24 US gallons). This would likely launch yourplant out of its hole in a matter of minutes!

That said, an appropriate amount will be significantly less -between a teaspoon and a quarter cup of crystals. It all depends onyour environmental conditions. In drought situations (no rain for morethan 28-days), you want a lot of polymer crystals to absorb any waterthey come in contact with - and it is unlikely that any single polymerwill absorb its maximum potential. A couple tablespoons to 1/4 cup ofpolymers is recommended for this sort of environment. In more "normal"meteorological conditions - a rainfall every seven to ten days - yourobjective is likely to minimize stress between rainfalls - and one totwo teaspoons would be the more than enough.

How do I use them?

The optimum use involves some experimentation for your soil andgrowing conditions. As a general rule of thumb, this method worked wellfor the FAQ author in extreme drought conditions (no rain for 60-days).First - make a deep hole - at least 3 feet (80 cm). An 8-inch postholeauger is very good for this as it completely eliminates theback-breaking work of shoveling - and if you are lucky enough to use apower auger - it will be very fast too.

Back fill about 6-inches (15 cm) into the hole and sprinkle atablespoon of medium-grade polymers over the soil. Continue backfillinganother 6-12 inches and gently work the polymers into the soil. Makethe soil wet with a couple liters of water and wait a few minutes. Thiswill allow the polymers to absorb the water and expand.

In the next 12 inches (30 cm) add any amendments plus anothertablespoon of polymers - pack the soil hard and when finished addanother couple liters of water. With the final soil - add your soilmixes and at most a third application of polymers - about a halfteaspoon maximum, moisten with a liter or two of water, and insert yourplant. Do not fill your hole to ground level with the soil - you willneed to leave at least a couple inches (5 cm) for expansion andheaving. The slight depression also acts as a natural pooling for waterin the environment - which is important in drought environments.

As an added drought protection measure, use a brown grocery storepaper bag as a liner for the hole (and mix the third half teaspoon ofpolymers in the soil in the paper bag). The paper bag slows thedrainage rate significantly - and takes about a month or two todissolve, in time to let the roots reach the deeper levels of polymers.

How many days will I be able to go between watering if I use polymers?

There is no real answer to this question because it depends on theenvironment and the plants themselves. In hot dry environments, theplants will transpire and loose moisture rapidly as compared to morehumid dry environments. Dry wind also has an impact on the rate thatplants transpire. Evening and night temperatures also impact the lengthof time that the polymers can hold water.

It is best to experiment and observe your plants, but as a generalrule of thumb, if used correctly, the polymers should buy an extrathree to five days between when you would normally water.

I once went 21 days between heavy watering in a severe droughtsituation. The plants with polymers, while definitely heat stressed,did not die; whereas plants without polymers did not survive this21-day period of neglect.






These Documents contain information gathered from many Online Communities and all possible references have been given to the authors of each individual article. For any discrepancies in this please contact "overgrow2@gmail.com" ....ps enjoy