TDS numbers

[rcb]

I do have to say its pretty amazing what was to me, very little difference in amount of fertilizer, the difference in the the plants are behaving. In the last month, the 15 Catt alliance plants that have bloomed, not one them is showing any of that nasty reddish color and premature leaf drop.

So yes, as my boys would say, it's all good dude.

Now, I am moving this week to a completely different part of Florida, with completely different conditions, so I'll probably be back in a month begging for advice again

But the good thing is I will be home more often, so I will be able to do a more daily care of them.

 

[ZWUM]

yes we're nuts and all self appointed experts on everything - just ask us!

Lol

 

[Rick]

This may stop some confusion:


EC (in dS/m) x 640 = TDS (in ppm)

1 dS/m = 1 mS/m = 1000 uS/m
1 uS/m = 0.001 dS/m.

So EC (in uS/m) x 0.64 = TDS (in ppm)

You should be able to work out anything you want form this with any meter.

That 640 constant varies considerably based on the salt composition. For straight NaCl and KCl it would be 500. For heavy sulfate based sytems something else. For heavy nitrogen based systems something else altogether. The only true way to measure TDS is by evaporating down the sample of water and weighing the solid residue.

The meter only measures conductance (or resistance) and does a similar calculation based on whatever algorithm and salt constant is programed into it.

So you may get a very poor correlation when you actually weigh out some fert and try to check it against a TDS meter.

 

[Rick]

I do have to say its pretty amazing what was to me, very little difference in amount of fertilizer, the difference in the the plants are behaving. In the last month, the 15 Catt alliance plants that have bloomed, not one them is showing any of that nasty reddish color and premature leaf drop.

Yes you only shifted from the equivalent of 2/3 tsp per gal to 3/4 tsp/gal.

May have also saturated out the binding sites in the potting matrix.

Also being at the mercy of the rain for flushing, its hard to say if your rainfall dropped by the same 13% increase in fert for the last month or so.

Or maybe the plants actually adapted?

But I'm glad your plants are still on track.

 

[Ozpaph]

Yes you only shifted from the equivalent of 2/3 tsp per gal to 3/4 tsp/gal.

.

It seems a lot to us metric people who have 4.5l per gallon and not US gallons (??3.55l/gal)

 

[Stone]

That 640 constant varies considerably based on the salt composition. For straight NaCl and KCl it would be 500. For heavy sulfate based sytems something else. For heavy nitrogen based systems something else altogether. The only true way to measure TDS is by evaporating down the sample of water and weighing the solid residue.

The meter only measures conductance (or resistance) and does a similar calculation based on whatever algorithm and salt constant is programed into it.

So you may get a very poor correlation when you actually weigh out some fert and try to check it against a TDS meter.

Yes it is only aprox. and differs with with salt types but most of the general ferts we use are very similar and I have used this for a long while without problem.

 

[Stone]

It seems a lot to us metric people who have 4.5l per gallon and not US gallons (??3.55l/gal)

Yes its about time the imperial system is relegated to history where it belongs

 

[Rick]

It seems a lot to us metric people who have 4.5l per gallon and not US gallons (??3.55l/gal)

Its 3.785

But I can round up to 4 if you want to round down to 4:wink:

 

[Ozpaph]

deal!