Runoff ppm question


A question from fellow grower:

I’m currently growing in soil with a 600w HID:HPS bulb and I’m in week 1 of flowering.

My plant’s runoff keeps coming out to over 1,000 PPM even though I have only been giving her Ph’d tap water (45-46 PPM). The most recent feeding she got was 340 PPM and that’s the highest one yet. All the earlier feedings were in the 200 PPM range.
I have strictly followed the feeding schedule of FWWW and yet I can’t figure out where all the extra PPMs came from. To me, she doesn’t seem to be showing signs of nutrient burn, she’s still growing fine but I’m confused as to how the PPMs got so high without me overfeeding her. Do you have any idea what I may have done wrong?


nutrients in the soil?


That was a thought that crossed my mind too. I’m using Happy Frog potting soil. I couldn’t find anyone else that’s having the same problem.


Fox Farm Happy Frog Potting Soil has a slur test ppm of between 800-900. If you are running any soil like this it has built in nutrients that will show during a runoff test. Nothing to be concerned about unless your numbers get really out of control. 1st week of using flowering nutes my PPM usually comes out around 1000-1200 if that helps. Different nutes and soils will swing those numbers a bit but should all be around the same. Your lady looks beautiful. Your doing good…Cheers!


I’m probably wrong here and I’ve never used Happy Frog but I do use ocean forest all the time and I thought that was the ‘hot’ soil ?

I thought Happy Frog was more like a pro mix type without much nutrient ?

I’m not disagreeing, I’m just asking, I’d like to know too ?

  • thanks


Hey @Paranorman I am not too familiar with soil to be totally honest. Spent many years growing hydro mainly DWC. As far as Ocean Forest goes I’m sure you did a slur test on it. PPM wise I would think it being a hot soil that it is in the 1000+ range. I have never used it before so I wouldn’t know. The nutrient line I use recommends a soil PPM of between 300-500 which is why I did the slur test. When I did so with Happy Frog I got a PPM of 840. The only thing I know of other soils is what people have expressed on here as well as other research I’ve done. I would like to use Pro Mix in the future just want to get some soil experience under my belt before I do so.

To do a slur test(at least how I do so) I take 4 cups of soil and add completely sterile water until it becomes a slightly watery sludge. I then measure with my PPM meter. Once I had those numbers it has help with my nuting regiment. I started out adding nutes with the same assumption that Happy Frog is like Pro Mix. It is not


Thanks for sharing that I also have a hydro background, this is only my second soil grow but I’m loving it

I haven’t had any issues with the ocean Forest being hot but I have read others who claim they have, I tend to think they might be feeding it nutes when it doesn’t need it but anyway I’m going to follow this thread thanks for the info


That is exactly my conclusion as well. With the Hot soils no real nutrients are needed until flowering although with the nutes I use plants seem to handle them just fine. Reason why I went with soil is quality over quantity. There is no comparison from a yield standpoint between hydro and soil just at this point in my life like I said I am in it more for the quality. I’ve only grown soil a few times over the years and its the taste that I can’t wait for. Last time I use soil I was using non organic nutes so taste here I am hoping will be even better. I’ve seen your posts. For only your second soil your killing it brother. Happy Growing!


Hey, thanks for the responses. It is in fact the Happy Frog soil I am using. I did a test to see about how many PPMs were in the soil. The results are in the pics.


And btw, this is how she looks now. :grinning:


Very nice looking girl