Basically anything desinged to trap waste like filter floss or foam blocks can cause nitrate issues because the food and waste just rots basically but with LR it will have bristle worms and pods and they will eat the waste and then the bacteria will break everything else down. I will say that you can use foam blocks but they will need to be cleaned every week.
I dont feel its needed and thats why good flow is important because it keeps most things suspended and lets it get to the fuge and or skimmer to be removed. If you want to run mechanical filtration I would only do it for a short time to polish the water then remove it but you will need to keep it all cleaned at least weekly. I havent run foam on my tank in 5 years and when I was running it I had hair algea and when I removed it the hair algea went away, I suggested it to a friend of mine and as soon as he took his foam pre filters off his hair algea went away also but you still need to do your regular WC's. I only clean my skimmer cup and do water changes and I just take the water out of my fuge then put the water back in the fuge.
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