# water and fertilizer rate



## paworsport (Nov 27, 2013)

Hi All,

I have a question regarding the proportion of fertilizer in water.

When I use my combo to meseare the conductivity of my tap water I have a figure of 250 ms. 
My rain water is betwen 30 or 40 ms

The good feeding for paph is 250 max 350 for multi like roth.

If I add fertilizer to my tap water to a level of 500 ms for example, do I give 250 ms of fertilizer to my paph ? 

I don't know if it is obvious for you but I don't want to make mistakes with fertilizer.

Thank you in advance for your help


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## NYEric (Nov 27, 2013)

paworsport said:


> If I add fertilizer to my tap water to a level of 500 ms for example, do I give 250 ms of fertilizer to my paph ?


No, you would be giving 500ms of "something" to your plants. You have to figure out what it is that you're giving them.


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## gonewild (Nov 27, 2013)

You have the basic idea correct.
However you need to take into consideration what minerals are in your tap water that make it 250ms.


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## paworsport (Nov 27, 2013)

Thanks a lot for your answers


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## Ray (Nov 28, 2013)

You also need to know the specifics for the fertilizer you're using.

For example, at a dosing of 50 ppm N:

MSU RO adds 0.4mS
K-Lite adds 0.35
MSU WW adds 0.34


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## Rick (Nov 28, 2013)

Check your units.

They look like micro siemens (uS/cm) not milli siemens (mS/cm). That changes things by a factor of 1000.

Rain water typically has very low conductivity, so I think you are actually tracking micro S. (If you compare to Ray's values that are mS/cm, and all less than 1.0).

The fertilizers are focused on supplement N, P, and K salts, while your tap water conductivity is mostly Ca,Mg and Na salts. So the conductivity values are really not related to each other. 

So you would generally add or subtract your tap water conductivity from the conductivity of whatever dose of fertilizer you add into a water of very low conductivity (like distilled, RO, or even your rain water).

I use RO water, but feed with every watering (which is daily for mounted plants). The conductivity of my final mix ranges from 60 to 80 uS/cm. Which is not much more than your rain water.

So you can get great results at very dilute feeding rates.


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## NYEric (Nov 29, 2013)

Rick said:


> I use RO water, but feed with every watering (which is daily for mounted plants).



What!?!?!


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## Rick (Nov 29, 2013)

NYEric said:


> What!?!?!



RO water is the base of my irrigation/feeding water.

All my mounted and open basket plants get watered/fed daily.

Stuff in pots or baskets with potting media get watered/fed less frequently. (maybe every other or third day).

Basically all water getting sprayed, hosed, or washed onto plants has a tiny bit of feed in it all the time.

Once a week I might add a 1/4 tsp per gallon of kelp extract on top of the regular feed/irrigation water.


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## NYEric (Nov 29, 2013)

Woohoooo!!! Time to buy more fertilizer!


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## ALToronto (Nov 29, 2013)

Not at all, Eric. I've been following Rick's advice and feeding with 10-15 ppm N every day for my mounted (living wall) plants. 
The results are great - photo 1 was a couple of weeks after mounting (with cable clips), in mid-August. 
Photo 2 is of the same plants, Nov.17. 

I'm using RO water, about 1/20 tsp epsom salts in 2 L of water (because my wall has plenty of Ca, but no Mg), 
and even less of PlantProd 20-20-20.

And this is in my living room, not a greenhouse.


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## gonewild (Nov 29, 2013)

ALToronto said:


> And this is in my living room, not a greenhouse.



Wow! That looks great.


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## NYEric (Nov 30, 2013)

I generally dont fertilize that often, so i will try to up the rate.


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## ALToronto (Nov 30, 2013)

Sorry, my fert isn't 20-20-20, it's 25-10-10. All urea-based - I'm still not sure why it's considered an inferior product for orchids. I used K-Lite on them as well, but they seem to prefer the PlantProd. I also spray them with fish/seaweed (Neptune's Harvest) once a week, also at about 15-20 ppm N.

Thanks Lance, I like it too. It's my little bit of rainforest, and I can keep over 40 plants on a 57*57 cm footprint. Even better than keeping them on a stove!


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## Ray (Nov 30, 2013)

ALToronto said:


> Sorry, my fert isn't 20-20-20, it's 25-10-10. All urea-based - I'm still not sure why it's considered an inferior product for orchids. I used K-Lite on them as well, but they seem to prefer the PlantProd. I also spray them with fish/seaweed (Neptune's Harvest) once a week, also at about 15-20 ppm N.
> 
> Thanks Lance, I like it too. It's my little bit of rainforest, and I can keep over 40 plants on a 57*57 cm footprint. Even better than keeping them on a stove!



Alla, I really don't know how you can tell what they "prefer".

Based upon my own experience, I'd say you'd need to do at least six months of identical other conditions, with the fertilizer being the only variable, before you could discern a difference. Maybe longer..


Ray Barkalow
Sent using Tapatalk


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## Rick (Nov 30, 2013)

NYEric said:


> I generally dont fertilize that often, so i will try to up the rate.



Increase the frequency , but reduce the concentration.

If you can measure conductivity, then drop the concentration so you are running a conductivity of ~50-80uS/cm. That is very dilute compared to the old 1/2 tsp/gal of MSU (conductivity ~800uS/cm) we used to feed weekly.

Just a tiny constant trickle of feed. Lots of water.

Keep in mind that plants "eat" water and CO2. The fertilizer (NPK.....) are really just the vitamin supplements.


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## Rick (Nov 30, 2013)

Al

That's quite an improvement on the wall. The concrete may be getting its P storage capacity maxed out.

Can you get a pH of water draining off the wall?

If you see some hints of blue green algae then consider cutting back another 25% on feed rate.


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## ALToronto (Nov 30, 2013)

Ray, these catts did nothing for a month while I fed them with K-Lite. Part of the reason was the high pH of the wall, and K-Lite doesn't reduce pH at all. So it could well be that the PlantProd worked simply by lowering the pH to a level where the roots could absorb the nutrients. The runoff water measures 6.3-6.4, so I'm happy about that. 

The water also picks up a lot of calcium from the wall. My plain RO water has 9-10 ppm TDS, and after I add Epsom Salts and fertilizer, I have around 90 ppm, with Epsom Salts being about 2/3 of the added amount. Runoff has about 300 ppm. Sorry, I don't have an EC meter.


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## ALToronto (Dec 1, 2013)

Rick, the algae is the result of my unsuccessful attempt to grow moss on the wall. I bought Moss Milkshake and spread it all over both walls, and watered it daily. What an utterly useless product! Or maybe I got a bad batch. The only thing I can get growing from the stuff I spread is this algae. I do have some live moss starting to grow on the tree branch in the photos I posted, and two more branches, but I don't think it's due to the Milkshake. Probably due to the mushrooms I keep picking off.


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## Rick (Dec 1, 2013)

ALToronto said:


> The water also picks up a lot of calcium from the wall. My plain RO water has 9-10 ppm TDS, and after I add Epsom Salts and fertilizer, I have around 90 ppm, with Epsom Salts being about 2/3 of the added amount. Runoff has about 300 ppm. Sorry, I don't have an EC meter.



Technically the TDS meter is and EC meter, but its just multiplying the EC reading by about 0.5 to convert to an average TDS for whatever calibration salt it was designed for.


Given that constant though, the TDS is still increasing by 3X coming down the wall. So still liberating lots of stuff from the concrete. It's not stabilized yet.


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## ALToronto (Dec 1, 2013)

I could probably stabilize it quicker by watering it with carbonated water! Not sure what it would do to the plants, though - could it actually help? If plants need CO2, would they be able to use it from the water rather than from the air? 

I might start looking for seltzer bottle kits...


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## Rick (Dec 1, 2013)

ALToronto said:


> I could probably stabilize it quicker by watering it with carbonated water! Not sure what it would do to the plants, though - could it actually help? If plants need CO2, would they be able to use it from the water rather than from the air?
> 
> I might start looking for seltzer bottle kits...



Although carbonated water starts out with a low pH, the pH climbs quickly as the CO2 burps out. If the substrate pH is still high, then much of that CO2 will get converted to bicarbonate ion and just support already too much buffered (high) pH.

I think just stick to what you are doing.


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## NYEric (Dec 2, 2013)

ALToronto said:


> Even better than keeping them on a stove!



Are yiou sure!? 



Rick said:


> Increase the frequency , but reduce the concentration.
> Keep in mind that plants "eat" water and CO2. The fertilizer (NPK.....) are really just the vitamin supplements.



Thanks. i keep it pretty dilute anyway.


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