HOW BARLEY STRAW WORKS
In order to use straw effectively, it is necessary to understand something of how the process works. When barley straw is put into water, it starts to rot and during this process a chemical is released which inhibits the growth of algae. Rotting is a microbial process and is temperature dependent, being faster in summer than in winter. As a general guide, it may take 6-8 weeks for straw to become active when water temperatures are below 50f but only 1-2 weeks when the water is above 68f. During this time, algal growth will continue unchecked. Once the straw has started to release the chemical, it will remain active until it has almost completely decomposed. The duration of this period varies with the temperature and the form in which the straw is applied and this will be discussed in more detail later. However, as a generalization, straw is likely to remain active for approximately six months, after which its activity gradually decreases.
When straw rots, chemicals in the cell walls decompose at different rates. Lignins are very persistent and are likely to remain and be released into the water as the other components decay. If there is plenty of oxygen available in the water, lignins can be oxidized to humic acids and other humic substances. These humic substances occur naturally in many waters and it has been shown that, when sunlight shines onto water which contains dissolved oxygen, in the presence of humic substances, hydrogen peroxide is formed. Low levels of peroxide are known to inhibit the growth of algae and experiments have shown that sustained low concentrations of hydrogen peroxide can have a very similar effect on algae to that of straw. Peroxides are very reactive molecules and will only last in water for a short time. However, when humic substances are present, peroxides will be continuously generated whenever there is sufficient sunlight. The slow decomposition of the straw ensures that humic substances are always present to catalyze this reaction.
There are various factors which affect the performance of straw and which support this hypothesis. It is important to take these factors into account to ensure successful treatment of algal problems with straw.
1. Type of Straw - We have tested a range of barley straw varieties, including some grown organically; all these were active at the same level. The claim that organic barley is better than non –organic barley is unfounded and totally unrelated to any studies done by any scientifically proven institution, and in fact, claims of seeded or pre-activated barley are totally false. There is only one way for the barley to be activated, and it is described above, any other claim is simply put, an attempt to sell more product and try to convince someone that their  product is better.

Do not use nylons or nylon socks or products that are packed in these. they will not allow enough water flow and you will get a horrid smell coming from your pond, Barely ball are supposed to float at about a half to 3/4 submerged point , do not sink the balls totally under water. They need sunlight and air and will not work well at all submerged to the bottom of the pond.The Nylons or very dangerous to fish  and they will be come intangled in them. The spines of the fins and and will get trapped in the nylons. If you want to see a example of this take a old or new nylon sock stretch it out over a wire hoop made from a coat hanger to make a net and catch a fish that you dont care about, you will see a perfect example of how entangled they will become!

The consumer must make a educated decision as to who they are going to buy from , a honest seller of the product, or a seller that claims false things simply to make a bigger profit .
2. The anti-algal chemical - The chemical released by the straw does not kill algal cells already present but it prevents the growth of new algal cells. Thus algae which die will not be replaced when the straw is present and so the algal problem is controlled.
3. Speed of effect - Once the straw has become active, the time taken for control to become effective varies with the type of alga. Small, unicellular species which make the water appear green and turbid, usually disappear within 6-8 weeks of straw application. The larger filamentous algae, often known as blanket weeds, can survive for longer periods and may not be controlled adequately in the first season if the straw is added too late in the growing season when algal growth is dense. It is, therefore, preferable to add the straw very early in the spring before algal growth starts.
4. Production of the anti-algal activity - Activity is only produced if the straw is rotting under well oxygenated conditions. Usually, there is adequate dissolved oxygen in water to ensure that the chemical is produced by the straw. However, if the straw is applied in large compact masses such as bales, or to very sheltered and isolated areas of water, there will be insufficient water movement through the straw, which will progressively become anaerobic (without oxygen). Under these conditions, only the surface layers of the straw will produce the chemical and so the majority of the straw will have no useful effect.
5. Absorption and inactivation of the chemical - The chemical is very quickly absorbed by algae and is inactivated by mud. Therefore, in waters which have high algal populations and are turbid with suspended mud, it is necessary to add more straw than in clear waters.
6. Selective effect on algae - The chemical does not appear to have any effect on higher plants. In our experiments, we have seen that the suppression of dense algal growth has allowed flowering plants (macrophytes) to decolonize waters which were previously dominated by algae. In several shallow lakes where straw was used, algae were replaced by higher plants which suppressed the subsequent growth of algae, so eliminating the need for further straw treatments.
7. Effects on invertebrate animals and fish - There are no reports of harmful effects on invertebrates or fish except in a few instances where excessive amounts of straw were applied to small ponds and the water became deoxygenated. These excessive doses were at least 100 times the doses recommended in this post. In most instances, invertebrate populations increase substantially around the straw so providing a useful food source for fish. There is anecdotal evidence that, in fish farms and fisheries, straw treatments may be associated with improved gill function and fish health and vigor.

The claims that net balls hurt fish are unfounded, they claim that small fry can get trapped in them, the net openings are 2/16 to 3/16 of a inch, it could be said with the same idea that any plants with roots that hang down could trap fish too, but thats not reality , that is a seller trying to use scare tactics to convince you thier product is "safe" , and the other is not.

Again the ethics of this seller should be looked at , just as they should be looked at for claims of "pre seeded" barley that is "organic". If you have anything added to a product that is "organic" then it is not organic any more.

Know the seller that you deal with and look at the things they say about thier products, if they make claims like snake oil sales men would , then act according to what you know is right. Do not be lead down a path that does not exist and pay more for a product than you have to, because of claims that sound nice, but really have no merit what so ever