I don't know anything about the other pump. I do know that you have to always use chlorine no matter what. Is the water a different color than it was? If so, I think you are getting rid of the algae. The water may be lime green because of staining - don't worry, you can get rid of that after the algae. The water will be cloudy until all of the dead algae is filtered out. You can try putting a leg that is cut off pantyhose in the skimmer basket. Put the foot of the leg in the basket, wrap the top of the the leg around the basket, put the handle back on, and put it back in the skimmer. It will filter some of the finer stuff out. Make sure you still have good water flow. You just want to get the water sanitized and clear. If you don't have a backwash position on your filter, don't worry about it. Just vacuum when the stuff falls to the bottom. I am not sure what kind of equipment you have, so bear with me. You would not have made the problem worse by adding chlorine. I think that the color of the water is staining - the chlorine should have killed the algae. You can try to put ph down in a sock, or crush some vitamin C tablets in a sock and rub it on the side of the pool. See if the liner changes color - if it does, then it is stain making the water appear lime green.