it's easier to prevent than to treat...
here's some info...
Under the right environmental conditions, virtually every plant species is vulnerable to Pythium, which not only causes `damping off' of seedlings but causes root and stem rot of older plants. Symptoms of Pythium on older plants are a wet rot, root systems will be browned, roots hollow and collapsed. Plants may appear to grow poorly, and wilt for no apparent reason - indicating that an examination of the root system is called for. Pythium has an optimum temperature range for infection of plants, this is generally between 20 - 30C (68 - 86 F), although infection can occur outside this range when damaged plant tissue is available for rapid colonisation by the pathogen. Low concentrations of Pythium that may not cause problems at lower temperatures will be disastrous at higher temperatures, particularly where the warmer conditions are associated with a lack of oxygen in the root zone and plant stress.
The best preventative measure against Pythium attack is a healthy, rapidly growing plant as this is an opportunist pathogen and will enter at the site of tissue injury or if the plants are overly succulent, weakened or stressed for some reason. Often root damage during the seedling stage as plants are introduced to the hydroponic system is a danger time for Pythium infection. Pythium is of greatest threat during the seed germination and seedling development stage when plants are most vulnerable to attack, and adequate control and elimination of the pathogen during this stage is the best preventative measure of Pythium control in hydroponic systems. Strong healthy plants will develop resistance to Pythium attack during the seedling stage and this will prevent problems at a later stage of growth.
Other preventative measures include the use of a well drained media, thorough disinfection of all equipment between crops (a strong hypochlorite solution - bleach is the most effective), and control of pathogens during the seedling stages with a suitable fungicide, long before they are introducing into your hydroponic system. Occasionally a very high spore load, combined with excessive temperature will result in Pythium attacking even healthy plants, if this is the case, it is likely that there is an active source of spore production present, and the system must be shut down and disinfected. Some growers have found the use of wetting agents and chlorination of the nutrient solution beneficial in limiting the damage caused by Pythium, however extreme care needs to be taken when using products such as calcium hypochlorite as to much active chlorine will kill sensitive plants. UV light, hydrogen peroxide and ozone have also been used to kill Pythium spores in the solution, however these can have major effects on some of the nutrient elements in solution and careful consideration should be given before using these methods. Sterilisation of the water supply with these methods, before nutrient are added however, is effective at reducing or eliminating Pythium from the original water supply.
Therefore by ensuring your plants are healthy and stress free, you will not only get the highest growth rates possible, but also prevent problems such as Pythium infection occurring. The variables to remember with regard to the nutrient solution is that aeration is vital to maintain the dissolved oxygen levels, temperatures should be keep within an optimum range, and Pythium is always present, but a healthy plant is the best measure of protection against a disease outbreak. About the oxygen requirement of plants when in flower...its not always the case that plants require more oxygen because they are in flower, a plants oxygen requirement is linked to the size of the root system, temperature and nutrient uptake rates, rather than the presence of flowering. So since plants such as tomatoes tend to have a rapidly developing root system at the time of flowering, its important to maintain adequate oxygen levels. With tomatoes the requirement of oxygen in the root zone increases gradually up until the time of maximum fruit load and rapid fruit expansion, where the high rates of nutrient uptake increase the oxygen requirement quite dramatically. On the other hand, if oxygen is deficient during flowering, then the flowers and subsequent fruit may drop off as a result, or they may be undersized and may fail to pollinate.
i don't really know what to tell you guys. i've used hygrozyme religiously for all my grows and i have never had a problem with root rot. in fact i'm using it during my current grow and my roots look great! are you using the product as recommended?? i think it calls for 8 - 10 ml per gallon and says to never exceed 15 ml per gal. it could be that the hygrozyme reacted with some of your other nutes. but i've used several different brands of nutes with no problems. what about res temps?? sorry about your problems, bro, but i wouldn't think about growing hydro without hygrozyme.
