hydroponics

[fool4fish1226]

Thanks fellers - Am I correct that I want the PH around 6 - I do have the strips, a pool type tester, and a cheap ebay one too. I guess I am on the right path. Thanks again

 

[JMichael]

I understand PH and why it's important, but why is the PPM so critical or what does it do for you exactly. And before someone says it, I know what PPM stands for, just not why it's critical to the plants.

 

[sunshine]

The ppm you're referring to is the unit for the total dissolved solids in your nutrient solution, ppm can also be expressed as mg/l . It it a rough gauge of the amount of nutrients available for your plants to uptake from the solution. Too high, the plant will lock up. Too low, you'll see deficiencies. It's not practical for folks to determine the actual levels of the individual compounds, nitrogens, etc so the conductivity/TDS is used for process control.

This is a good chart for pairing up different plants and getting a good starting point as far as pH and nutrient levels.

https://www.homehydrosystems.com/ph_tds_ppm/ph_vegetables_page.html

 

[JMichael]

So you're saying that just like different plants may like different PH levels, they also may want different nutrient levels and that's what you are checking with the PPM meter, the amount of fertilizer/nutrients in the water? Or it's basically a way of checking the ratio of fertilizer/nutrients to water?

And if the above is correct, then all the PPM is telling you is the ratio of nutrients to water but that does not necessarily mean you have the correct parts (ie nitrogen, potassium) that that particular plant may want?

 

[SumDumGuy]

So you're saying that just like different plants may like different PH levels, they also may want different nutrient levels and that's what you are checking with the PPM meter, the amount of fertilizer/nutrients in the water? Or it's basically a way of checking the ratio of fertilizer/nutrients to water?

And if the above is correct, then all the PPM is telling you is the ratio of nutrients to water but that does not necessarily mean you have the correct parts (ie nitrogen, potassium) that that particular plant may want?

Yes.

It is a way of checking the amount of fertilizer/nutrients in the water. Total Dissolved Solids measured in parts per million for a given amount of water.

Total Dissolved Solids (TDS) are the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water, expressed in units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm).

Correct parts or ratios of fertilizer are determined prior to addition to solution. For example you may start out with a 4-18-38 fert (known ratios of the big 3), and then add this "stuff" to your solution until you get to the EC or TDS that you want. Low TDS or high TDS you will still have the same ratio of fertilizer parts, just at different concentrations.

 

[sunshine]

Yes, you are correct. Determining the actual levels of those individual nutrients is cost and time prohibitive for the average DIY guy. When preparing your solution you dose according to your targeted plants liking with the assumption that they will consume it proportionally to their published needs.

Knowing your conductivity/TDS is not necessary by any measure but just helps you dial it in a bit better. Otherwise you are waiting for your plants to show you signs that the solution needs changed out or doing it on a time schedule, which may result in either wasted nutes or slowed growth.

Also, if you are intending on using municipal or well water instead of distilled or RO water in your nutrient solution preparation, consider the nutrient/mineral levels (hardness) in your starting water when calculating your additions, this will vary greatly by location.

I mentioned it previously, but it's also good to give the plants a day or two of clean water lacking any additions in between every couple/few solution changes to flush any salt build up out.

 

[Butthead]

I was totally thinking this was going to be a Colorado discussion.