It would be better to reduce your chelation to a maintenance dose when your Hb drops below 500. Don't stop at 1000. You need to be cleaning up the new free iron, which is very easy to do at low ferritin levels, as long as you continue to chelate. Without a chelator present, this free iron can cause damage, including to the red blood cells, causing a faster breakdown. This may be why you see an increase in spleen size when you don't chelate.