Here is another link in case you want to get 5 lb.:
http://www.msm-msm.com/store/agora.c...scorbic%20Acid
You bring your ph down, and lower your chlorine (the ascorbic acid will be used up by the chlorine) Just pour the ascorbic acid down the walls of the pool as you walk around. Put the filter on circulate, dump in enough metal sequesterant for the size of your pool and let it circulate till you see all the stains magically disappear! It doesn't take long. Then put your filter back to filter and keep it on 24/7. After 24 - 48 hours you can start to SLOWLY bring up your chlorine level. If you have a sand or DE filter you can put a chlorine puck in the skimmer, which will help to let the metal stain the filter instead of the pool. Youwill also have to bring up your ph level. After a stain treatment it is hard to keep the ph and chlorine up. Don't let the ph go higher than 7.2 for a while, and do not get your chlorine up to shock levels for at least 2 weeks. High ph and high chlorine will make any metals in your water percipitate back out to land on the pool. If you have any questions feel free to ask.