Ppm/flush questions

I received my TDS meter Weds. I finally got to check it out and my PPM was OUTRAGES!!! So I flushed yesterday it’s worthy to say my soil pH was on the low side.
This leads me t a few questions

  1. this morning my bud sites (I’m in the middle in veg) aren’t as green as before. Before the flush everything was a mostly the same shade of green. Now the bud sites (or nodes or soon to be bud sites ( idk if they’re nodes if they grow a bit) anyways the tips of new growth is lighter green. I believe this is a good thing if my memory serves me right. Means the flush is doing its job. My plant must have had too much nitrogen because everything was darker I’m assuming.

Also while look up flushing stuff (it’s hard finding veg flush stuff online most of it all is last two weeks of flower… I digressed again I found that fox farm s suggest using sledge hammer bushwhacker stuff… What exactly is/are these flushing agents? I thought were flushed to get rid of stuff not add more!!!

Lastly I have another plant that just started it’s second week in flower. If that ppm is outrages as well is it safe to flush in the first two weeks of flower???

Lastly I tell you how much of a fool I am. I had no metter and was doing what they said cal mag and feeding half strength. My ppm was 8k!!!

The Fox Farm fertilizers are very salty. Sledgehammer helps wash out the built up mineral salts.

They are called surfactants and what they basically do is make the water more wet. It makes the water more effective at loosening the hardened mineral salts and washing them out. It also enables a more effective flush with fewer gallons of water.

The way they work is that they reduce the surface tension of the water.


Do you best to maintain a runoff PPM of ~1,000.


I didn’t have a TDS meter. My friend who showed me doesn’t use one. And didn’t get that “technical into it” I have a meter now! I brought the pH to 6.2 and the ppm to 1500 I know it’s a bit high still from that was three five gallon buckets later!! I will very adamant about it now. What I’m uncertain about is what to do next.


Much better. The ideal pH is 6.5, though anywhere in the range 6.3 to 6.8 is acceptable.

Skip a feeding or 2 to get the PPM back to ~1,000. No need to flush again to wash out the remaining extra 500 PPM. A plant will consume that in a period of several days.


Obviously I know t wait to feed till the ppm gets below say 750. And what do I put in at a time I guess I have to make a nutrient mix at half and see what the ppm is. My water is around 150. So do you want to aim a little higher putting in?
So if my ppm is 600 and my target is a 1k do I add 400 or do I go over a little expecting some to be loss

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There are no specific formulas for getting there as each plant and each unique environment will be different. It will take some trial-and-error experience to be able to effectively maintain that 1,000 runoff PPM. If using FF nutes, then feed 1/2 to 3/4 of the FF recommended amounts and adjust as necessary to achieve that 1,000 runoff PPM. Don’t worry about it if you overshoot or undershoot a little.


From what I’ve read it seems I kept adding nutes once a week and call mag once a week (not same feeding) so the unspent nitrogen lowered the pH. Which then aloud my plant to only take so much. Stunting growth some changing colors etc.
I’ve since fixed the problem. I transplanted (unrelated two days ago or so)and fixed my hot ass soil last night. My plants have grown more in the past two days then they have the past week


It’s not necessarily unspent nitrogen. It’s the salt buildup that results when using FF products. It is the salts in a form that the plant cannot use that bonds to your grow medium. The mineral salt buildup I referred to above is what submarines growers’ pH. It is why FF recommends intermittent flushes.

You can minimize these mineral salt issues by switching to a less salty product like Jacks 321.

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That’s good to know. I’m gonna finish these grows with what they started with. My next im considering to try coast of Maine and organic. However I will definitely look into jacks. 321 Ive heard about it on here before

I was referring to the drop in ph

From what I read unspent nitrogen will lower your ph

The lock out prob helped me from destroying my plant

Sort of. It’s an oversimplified way of looking at it. The primary factor is the salt buildup that occurs. Unspent nitrogen can be absorbed by a plant. Hardened mineral salts cannot be absorbed by the plant and it is those salts that submarine your pH.

Ohhh that’s what you meant submarine your pH. Lol.

I’m just trying to figure this thing out. I appreciate it!!

It has been a while since I have used soil. When I did I used fox farm’s Ocean Forest.
OF is a nutrient rich soil and not uncommon for it to have ppm in the 2000+ range. My feeling is don’t chase numbers if the plant is happy. However, pay attention to the direction the numbers are heading. For example if ppm is going up and ph is going down it is usually an indication of nutrient build up in the soil. To correct usually dropping nute intake or water only a couple of times will take care of it.

I hope you aren’t flushing soil to get the ppm down. You are removing the nutrients from the soil that are needed to feed your plant over the first month or two. If you want low ppm in your grow medium I suggest you switch to coco or hydroponics.

It is normal for a new bag of soil to have ppm of 4000-6000.

@CMichGrower that’s confusing considering everything I heard was contrary that you don’t want a high ppm that’s how you burn your plant. I’m feeding synthetic nutrients. And my plant is over a month old. I was in lock out due to too many nutrients

There’s a very big difference between a reading of 4000 ppm in a fresh pot of soil, and 4000 ppm from salt based nutrients. The high ppm readings you get in runoff from a charged soil like Ocean Forest is safe for your plants (other than new seedlings sometimes) because the ppm’s are coming from the organic materials breaking down in the soil.

If you mixed a feeding of Fox Farm trio to 4000 ppm’s and poured it in, your plants would not be ok, but 4000 ppm’s coming from the runoff of fresh soil is fine.


@BassNBricks, to answer your last post more specifically, if your plant has been in that soil for a month, and you’ve been watering/feeding with proper runoff, then you are correct in that your high ppm’s were a result of your nutrient input. And as @MidwestGuy told you, that’s very common with FF trio nutrients.

If you had just transplanted into that soil recently, then the high ppm’s would be totally normal and acceptable.