scooby250

I just got a TDS meter for my aerospring system. Everything was going great i just wanted to have more control over nutrients. I was wondering what a good range for PPM is i heard somewhere between 300 and 400 is good, im at 363 right now.

Aerobuds

There are a couple of factors involved in trying to determine the propper PPM range.

1. Different types of strains can handle more PPM than others.

2. The kind of nutes you are using will make a difference in how high of a ppm you can use. My experience is that the more chemical your nutes are(Opposed to organic) The lower the PPM your plants will be able to handle.

3. The kind of water you are using will make a difference in the PPM

To find the maximum PPM you plants can handle you should add nutes every couple of days to raise the PPM.

When you you see the tips of your leaves to burn, You know that you are at your mamimum PPM for that type of strain.

Then just add some water to your nutes to bring the PPM down a little to keep them from burning.

BTW I run my PPM around 900 until the 3rd week of flowering, Then I raise it to 1100.


Aerobuds

malibu

unfortunately your ppm TDS meter only measures conductivity, so all you really can ever know is the conductivity of the aqueous solution.

the conversion to ppm is usually 0.5 times the conductance EC measured in microsiemens/cm.

if you are reading 353 ppm on a meter that uses 0.5 then all the meter has done is measure 706uS/cm of conductance (distilled water with no other ions measures 0 conductance and 0 ppm)
if you started with distilled water and added nutes only then the EC of 0.706 would really be closer to 494 ppm of your nutrients in water (706 x 0.7)

but if you started with hard tap water with CaCO3 then that 0.706 EC is about 353 ppm 'cause the conductance is due to calcium carbonate ions

since this server times out longer posts we'll have to post multiple -since re-writing all the time is a pia

malibu

[
and now to really confuse things ...

if you add an organic tea to some known ppm solution of nutes, the reading will probably go down even though you added more substances/solutes and really more parts per million of stuff

the tea/organics actually will block some of the conductovity through the solution, like an aqueous insulation

this is the kind of reason why some meters up the conversion to 0.7 if they are used for agriculture/fertilizers as compared to simple salt ionic solutions which only have small ions when they derive the ppm number you see on the display from the conductance that is really being measured.

so what kind of meter, what kind of nutes ?- if the plant is older than seedling it seems like you could go up unless your adding earthjuice or something making the number lower than it really is.
i'm out before I get timed out.

scooby250

I really dont know what kind it is i think its a hanna, i just got it yesterday here is the auction i got it from. I am using futuregarden's above and beyond nutrients and my plants are about 2 weeks old. Thanks for the help

malibu

TDS1 is, or maybe was, a Hanna model - they may have discontinued it.

I'm up to 1030 ppm already -computing from an EC of 1.470 that would mean you would get 735 ppm on your TDS1 (there are no specs at Hanna website like there are for other models) = I'm assuming it converts to ppm by multiplying by 0.5 as most meters in that range are measuring hard water and the like, not nutes.

using dyna-grow (with dyna-bloom later) and a gallon of 10-3-3 bat guano tea mixed in per 7 gallons -
the tea dropped the EC and hence TDS by about 50 ppm

for the record, Canna grow is 22-8-28 and Canna bloom is 19-11-35
sure would like to get my nitrogen up, some of the ozzie mates using it I think run up around 1900 ppm

also since your meter only goes to 999 ppm you can take a sample out and dilute it 50-50 with distilled water to test when you get above 1000 ppm

any questions, let us know. good luck.