Well mine looks transparent and for the lack of a better term, rather watery.
Sorry, had to do it. Been up too long and I am punchy...
So, my tap water normally comes out at 170 - 180 PPM, but we do have some fluctuations of the mineral content though as our city water is pulled from the Pueblo reservoir on the Arkansas river. Once in a while (maybe every 3 years or so) we see spikes of magnesium. I watch for that and when it happens the PPM goes up above 200 to around 230 - 250 PPM but our city water engineers say it's just magnesium and indeed you get those yellow stains on sink drains like where you get orange/rust colored ones from high levels of iron. I have found that I just need to minus out my normal tap water epsom salt input when the magnesium spikes. Thats the nice thing about RO water, unless the filter is needing changed you are always working with a clean slate.
When I switched from RO to tap water I learned that I needed a little calmag to get the calcium where the plants want it and I need a little epsom salt to bump the magnesium more without adding calcium. With RO water I was using 5ml per gallon of calimagic and no epsom salt unless running coco. With tap h2o I am only using a hair over 2ml of the calimagic and a third of a gram per gallon of epsom salt for magnesium.
All in all if I was running DWC I would probably go back to RO water for that. I am fine with tap water when running peat based soiless mixes like Promix, coco or flood and drain with LECA.
Everyone's tap water is different and often if you know how many mg/l of the different elements it contains you can often correct your feed to compensate if something is problematic. If I had water that was over 250 mg/l (PPM) TDS then I would send it to a lab and have it tested.
One thing that I will note is that, PPM as measured with an electronic pen, is just an estimate based on the EC (electrical conductivity) of the solution. Different minerals in the water will conduct electricity with different levels of resistance. Therefore adding 10 mg/l of one compound or another could cause different reading on the EC meter based on how conductive the compound is. mg/l is an actual parts per million number often referred to as "elemental PPM". These numbers can be measured with lab equipment or calculated using product label percentages.
