PPMs of what, exactly?
Could be why it seems that your filter doesn't "work". If the carbon filter is only designed to remove chlorine, but the ppms in your water is chloramine or something else then your filter won't "catch" them because it isn't designed to do that.
If you need to remove chloramine from water, it takes a bit of extra effort but is very much doable.
I would fill a sturdy rubbermaid tote with my tap water, then bubble it with airstones and chloramine remover for 24 hours or so.
Something like this will work.
What nutes are you using? Bottled products or organic top dress?
FFOF is good stuff, capable of being a good quality living soil. The problems arise when you use Fox Farm's bottled products, these products are synthetic and will kill off the microbes in your soil. This will effectively turn your grow into a psuedo-hydro grow, with the soil as the substrate.
Unless your plant is a heavy feeder, FFOF should last a young plant for 6-8 weeks. The benefit of a good top dress is that you can top dress 4-6 weeks in, this way it will be readily available in the next few weeks after decomposing.
Neem/kelp/crab meals combined are all you need for a top dress.
Once my seedlings are around 4 weeks, I top dress with neem and kelp meals, then cover that with compost. I do this every 1-2 weeks during veg, supplementing with fish emulsion in veg if a strain is a heavy feeder.
During flower, I like Dr Earth's "Life Organic All Purpose Fertilizer (4-6-5 NPK) because its a nice balanced blend of amendments that won't cause issues in the form of being "too hot". I supplement with fish hydrolysate during flower for heavy feeders.
You'll notice I omit Crab Meal; its amazing stuff but my water has so much calcium carbonate in it that the calcium levels in Crab Meal combined with my water results in Calcium toxicity. If I used RO water, I'd definitely use Crab Meal.
Be mindful of the contents of your water when considering nutrient blends/amendments.
Your first step is looking up your city/county's water report and finding out what the 180-200ppms consist of, then use that information to plan your nutrient regimen accordingly.