TDS meter stabilization and proper levels

My TDS reading is constantly climbing (it seems to have stopped).

My reading is around 880 ppm.

My hydro recipe calls for 15mL of grow per gallon. That and pH down is all that's been added. Does everything sound okay? Also, what should my pH be? Around 5.8 right?

5.5-6.5. I prefer 6.2. also in dwc, 500-800ppm.

Plants are looking a little yellow. Amy ideas?

Greggl4321 said:

My TDS reading is constantly climbing (it seems to have stopped).

My reading is around 880 ppm.

My hydro recipe calls for 15mL of grow per gallon. That and pH down is all that's been added. Does everything sound okay? Also, what should my pH be? Around 5.8 right?

Click to expand...

If your ppm is constantly rising the nutrient solution is too strong. They're taking more water than nutrients. Ideally you want to see the Ppm stay the same but the water level go down. I keep my ph at 5.8 depending on if I see deficiencies. If plants are yellowing it's probably nitrogen deficiency. Do you have a good amount of nitrogen that you're feeding them? If so, bump the ph up to 6.0-6.2. Nitrogen is taken up better at those ph levels.

I'm not growing in dwc, but coir.



What should the ppm of my nutrient solution be? Is this including the ppm of the tap water?


What is the danger zone?







Should I water every day or let the roots dry a bit so they grow bigger in search of water?

You should never let coco dry. If you don't already, it's good to have a layer of hydroton of grow stones on the top to limit evaporation and to deter fungus gnats. It's almost impossible to overwater coco - it just holds the right amount of water, lets the excess runoff and has lots of air gaps for O2 to the roots.

In my drip systems I feed 2 or 3 times a day depending on the plant and pot size. When it dries all the way, the fine root tips die back and need to be regrown each time, losing resources. Keep it moist.

Add your tap water ppm to your expected. So if your tap is 150 and you want a 750 target ppm, your end ppm should be 1000.

How old are your plants and how big? Do you have a pic?

And when you say it's constantly climbing - what are you testing? A fresh batch of nutes before you feed - and the meter doesn't stay stable right after mixing? Do you mean over time? Or runoff ppm?

FennarioMike said:

Add your tap water ppm to your expected. So if your tap is 150 and you want a 750 target ppm, your end ppm should be 1000.

Click to expand...

Do you mean 900ppm? I had this same question in a thread I started a few hours ago, wondering if I should subtract the tap starting ppm from the nute total ppm I'm going for.

So right now my res is around 400ppm, and my tap water began at 200ppm. That means my nute ppm is only 200, right? Odd because that is pretty low nute value, yet the plants aren't showing any sign of deficiency. They're not even a month old though. Seems like I'll be going into flower before I really even start adding a higher veg level nute level.

BadlyDrawnBoy said:

Do you mean 900ppm? I had this same question in a thread I started a few hours ago, wondering if I should subtract the tap starting ppm from the nute total ppm I'm going for.

So right now my res is around 400ppm, and my tap water began at 200ppm. That means my nute ppm is only 200, right? Odd because that is pretty low nute value, yet the plants aren't showing any sign of deficiency. They're not even a month old though. Seems like I'll be going into flower before I really even start adding a higher veg level nute level.

Click to expand...

yes. But a TDS meter reads on the 500 scale and a regular conductivity meter might be 700 scale. The one I have can do both of those and EC. So, 400ppm 500 scale = 560ppm 700 scale. Unless your feed chart specifies TDS, it's probably giving you a 700 scale value.

Here's a conversion chart - https://www.bluelab.com/knowledge-base-files/Conductivity-Conversion-Chart

I found a site that says advanced nutrients uses the 700 scale, but i don't see anything about feeding and ppm numbers on my bottles or on their website. The only dosing instructions they give are ml per gallon.

So because they use 700 scale, my measurement of 400 ppm right now is actually 560ppm?

My tds pen does ec measurements also. Maybe I should measure in that, it seems to be less confusing/more accurate because there is no different scaling with that measurement.

BadlyDrawnBoy said:

I found a site that says advanced nutrients uses the 700 scale, but i don't see anything about feeding and ppm numbers on my bottles or on their website. The only dosing instructions they give are ml per gallon.

So because they use 700 scale, my measurement of 400 ppm right now is actually 560ppm?

My tds pen does ec measurements also. Maybe I should measure in that, it seems to be less confusing/more accurate because there is no different scaling with that measurement.

Click to expand...

Yeah - a lot of people prefer EC because of that. But... a .1 increase in EC is 70ppm. When I'm monitoring my plants I want to know what kind of trend is going on with the ppm - is it rising or falling. Since the 700 scale ppm uses a larger number, you can see these trends long before you would with EC. Just my preference...

Also, lets say you wanted 50 ppm of silica, that's less than .1 EC - you couldn't read that low

Ec/ppm goes up, PH goes down=plants require less nutes.
Ec/ppm goes down, PH goes up=Plants require more nutes
Ec/ppm stable, PH goes up=Equilibrium=Good thang.