Chem77 said:

No meter reader here. I like to push the plant as hard as I can, they will tell you if it’s too much.

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Aqua Man said:

Absolutely but why start over guessing how hard to push the same strain each grow. By taking notes of a strain you can maximize the light intensity over a couple grows and know exactly when to increase to what.

I say this because dialing in a grow is not going by a set of ideal parameters given. Everything from genetics, wind, watering, media, nutrients, temps, humidity, co2, pruning etc. can and will effect how much light the plants can handle. So keeping a record allows you to see if a slight change has improved the amount of light they can absorb and thus hkw much energy they can produce for growth.

I mean there is nothing wrong with simply going by the plants. But if you want to truely dial in a grow to maximize the potential of a plant then you need a way to measure and record the variables that affect growth so you know 3+ grows down the line what you have done and how it affected the growth of a specific strain and pheno.

A lot of ppl are happy with some good bud to smoke and less hassle of keeping records and taking all these unnecessary measurements to do so and nothing wrong with that.

I'm only stating a way that home growers who desire to truly optimize a grow and further thier knowledge and understanding by seeing how measured parameters can really help thier end results at the cost of bit more time and equipment. Which I feel is beneficial because cannabis is not a one size fits all plants and needs, tolerances and results can change drastically between strains and phenos.

Is it worth all the extra work? That depends on the grower

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Chem77 said:

I try to keep it stupid simple. My preferred method is to grow 9 plants in 5-7 gallon fabric pots under 2 GC 680’s. I grow 8 of my wanted/desired strain and 1 odd ball. The odd ball goes in between the two lights, gives a little leeway/tolerance for it. Basically it’s all about the 8.
I agree, you get what you put into it!

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Flat_Eric said:

Only EC exists. PPM can't be measured by the kit we are sold. You can pick up two of the best PPM meters, both properly calibrated, and get readings 40% apart. Then boil off the solution and weigh the dry matter, to find both were wrong anyway.

The problem is, that PPM isn't being measured by the PPM meter. No. The PPM meter is measuring EC and then using a conversion factor to guess PPM. Much like using a Lux meter and correcting it for PAR.
As in my previous post, the Lux to PAR conversion is different for different meters. With the EC to PPM conversion, it's different for every salt. Opening up the issue further, you can use a PPM meter to make up a solution in two reservoirs, with a different feed in each. set both for 1000ppm, and there is no real hope of both being 1000ppm in reality.
PPM's exist when you weigh the stuff in yourself. Then you measure the EC, and monitor it. That is the truth. Converting to PPM is just kidding ourselves. It serves no purpose. It just introduces errors that are accepted as 40% between meters. So when you read someone chatting away in PPM, it's quite useless information in regards of neutrient strength. Just as with people measuring lights with smart phones.


To give ourselves a chance of sharing numbers, I used this meter beside a known meter. I can only tell you this meter says 20,000 at 600 and that's not transferable to any other meter

It's a good job I posted that image.. I imagined a button. It has just 3 not 4.

I plotted it out (did I say?) and it was linear to about 800ppfd, where I ran out of light to test further (I was being lazy. I could of moved it, but had what I needed)


When people talk Lux or PPM without sharing their equipment, it's not usable information. The internet has years of records regarding peoples grows, that are near useless because they used unknown measurements. Spoons. Eggs. Gallons. PPM's. Lux. Frankfurters. It has to stop. People have their boots on their own necks, holding themselves down.


I'm ranting again aren't I. Totally gone off on one. Left the building, made it to the airport and boarded for lala land. Sorry :)

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Flat_Eric said:

Only EC exists. PPM can't be measured by the kit we are sold. You can pick up two of the best PPM meters, both properly calibrated, and get readings 40% apart. Then boil off the solution and weigh the dry matter, to find both were wrong anyway.

The problem is, that PPM isn't being measured by the PPM meter. No. The PPM meter is measuring EC and then using a conversion factor to guess PPM. Much like using a Lux meter and correcting it for PAR.
As in my previous post, the Lux to PAR conversion is different for different meters. With the EC to PPM conversion, it's different for every salt. Opening up the issue further, you can use a PPM meter to make up a solution in two reservoirs, with a different feed in each. set both for 1000ppm, and there is no real hope of both being 1000ppm in reality.
PPM's exist when you weigh the stuff in yourself. Then you measure the EC, and monitor it. That is the truth. Converting to PPM is just kidding ourselves. It serves no purpose. It just introduces errors that are accepted as 40% between meters. So when you read someone chatting away in PPM, it's quite useless information in regards of neutrient strength. Just as with people measuring lights with smart phones.


To give ourselves a chance of sharing numbers, I used this meter beside a known meter. I can only tell you this meter says 20,000 at 600 and that's not transferable to any other meter

It's a good job I posted that image.. I imagined a button. It has just 3 not 4.

I plotted it out (did I say?) and it was linear to about 800ppfd, where I ran out of light to test further (I was being lazy. I could of moved it, but had what I needed)


When people talk Lux or PPM without sharing their equipment, it's not usable information. The internet has years of records regarding peoples grows, that are near useless because they used unknown measurements. Spoons. Eggs. Gallons. PPM's. Lux. Frankfurters. It has to stop. People have their boots on their own necks, holding themselves down.


I'm ranting again aren't I. Totally gone off on one. Left the building, made it to the airport and boarded for lala land. Sorry :)

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