There really is no set time limit with the filters. You should also optimally have a triple inline tds monitor. You place it on the source water, before the membrane, and after the DI resin. You should also have a flow restrictor that allows flushing. You can open and close it. You want to make sure you fluah the unit for a few minutes before you make water. You'll see the tds rise and then fall again. Thwn once it flushes out the creep, you re engage the restrictor. I use a 3-way ball valve that allows the water to bypass the DI resin when flushing. It goes after the membrane and you run one side to the drain and the other side goes to the DI resin. So when you flush, you switch to the drain side, then switch back to the resin when making water. As for the sediment filter, there are different qualities and different micron ratings just like filter socks. You generally don't want a large micron size because the sediments can get through and clog the carbon block. I use a 1 micron sediment filter that is a high quality and lasts longer. If you have a lot of sediment and go through the filters fast, then a 5 micron would be used. Next, the carbon block. Being you have chloramines, I would stick with the universal carbon block from BRS that you probably got. It's blue. The way I measure the carbon block is to see if there's chlorine in the water. Don't have experience with chloramines. The membrane. You should make sure to flush before making water and when your rejection rate gets below 90% you chuck it. They say it has a 98% rejection rate, but that's at 77 degrees. Warmer water will pass through the membrane easier than cold will. Most people just use cold water, but the rejection rate will be lower because less water will pass through the membrane. Using warmer water will increase the amount of sediment from your hot water heater or water tank. You can see a higher tds on the source water if you run it luke warm. Lastly, the DI resin. Are you sure you have color changing resin? You can either manually add DI resin to a canister, and it must be packed tight, or you can buy a premade resin block. I typically use the Spectrapure High Capacity Silicabuster DI Resin. It's the best available in dealing with silicates in the water, which cause diatoms. Hope that helps.