Any suggestions on the above questions?

No you don't need to foliar spray at all unless pests become a problem. Where I'm from spider mites are prevalent and I spray on a regular basis with Organocide as a precautionary measure.

Yep, the roots on some strains grow very rapidly.

Here's a lil info on hydrogen peroxide.
http://www.dutchmaster.com.au/?language=english&page=growers_guide&topic=hydrogen_peroxide

That's a good link about the h2o2. I always thought of it as a band aid type fix to temporarily raise your dissolved o2 level, if the system is built with the right aeration and temp, you should never need it.

What link do you mean Harvey???

LOL, for some reason, my browser showed your post Harvey and not the previous one with the link, sorry about that!

I'd like to make a small point, i.e. EC is what PPM and TDS are based on, and not every meter brand arrives at PPM or TDS in the same way.

In the Aqua Flakes feeding chart, for the first week of growth, they specify a nutrient strength of 1.2EC and a PPM of 840. They arrive at the PPM, by multiplying the EC *700. Not all PPM meters use 700 as their multiplier.


What brand PPM meter do you use? What brand TDS meter do you use? (There can be a few extra multipliers for TDS measurements, 640, 650, and 680 are three that I've read about).

What brand do those on this forum, that told you to keep adding nutes until the EC/PPM was up to about 250-300PPM, use?

Most meter manufacturers in the hydroponics industry use one of two conversions, but there are others.

There is the 40% sodium sulfate, 40% sodium bicarbonate, and 20% sodium chloride, conversion which is approximately 700 x EC in millisiemens (mS).

Then there is the NaCl, sodium chloride, conversion which is approximately 500 x EC in millisiemens (mS)."

For instance, the Hanna EC/PPM meters use a multiplier of 500 while the Eutech meters use 640 as the multiplier. My Bluelab Truncheon uses both the 500 and 700 multipliers, with two different values in two separate columns, both read as PPM.

In the Aqua Flakes feeding chart, for the sixth week they specify a nutrient strength of 2.0EC and a PPM of 1400. A Hanna meter would indicate 1,000 PPM for an EC of 2.0. If you raise the Hanna measured mix to 1400 PPM, you've actually raised your EC to 2.8, way too high.

Do you see how the numbers that you are trying to compare via posts, may differ on PPM but actually be the same EC?

The point is to make sure you're comparing apples to apples in order to answer your questions via these forums.

"How much should I be concerned about the PPM reading??" If you wish to stick to PPM, and as you are using the Aqua Flakes feeding chart, and they use 700 as their multiplier, you'd first want to make sure your meter is using 700 also.

PPM is a valuable tool but when comparing numbers between meter brands, it can be complicated. If you can give and receive your information in EC, you do away with the differences in brands and multipliers.

I hope this helps, just something to keep in mind when comparing posted PPM values to what you read on your meter... 52.

PS, Get a better pH meter.

I have a hanna 98129, and while it's been a while since I was in the setup menu thing on it, I'm pretty sure you can set the EC to tds conversion to whatever you want..

Blue Lab combo meter. Love it and the warranty. Been usin' it for over 3 years now and not changing a thing.

Harvey,

When I was reading up on the different conversion factors, I ran across this adjustable meter. I left this model out so as not to confuse the issue which was, when posting or reading a PPM measurement online, one cannot make a comparison unless they know what multiplier was used at the other end, and that using EC would solve any confusion.

The Hanna 98129 has an adjustable EC/TDS conversion factor range of 0.45 to 1.00 mS/cm (450 to 1,000 uS/cm) and is a great unit to have. If I tell you that my meter uses a multiplier of 680, you can set your conversion factor accordingly. Then we can compare apples to apples.

With EC, electrical conductivity, there is no need for a PPM multiplier, adjustable or not... 52.

Nutogrow... not even batteries? lol

I have the Bluelab Truncheon and I'm not changing anything either. It has dual PPM scales (*500 and *700 uS/cm), CF, and EC.

I'm not advocating purchasing a new meter.

What I'm advocating is, when posting a PPM measurement, to let the reader know which conversion factor was used or state the EC directly so that an apples to apples comparison can be made. This cannot be done by stating the PPM measurement alone.

For instance, say we live on opposite sides of the Atlantic and are trying to duplicate results. Your meter uses a EC*700 multiplier and mine uses EC*500 but we have not communicated this information.

For a certain week, you specify a nutrient strength of 1400 PPM. I bring my PPM up to 1400. My plants start dying from what appears to be overfeeding. Why?

On your meter you would divide 1400 by 700 to get an EC = 2.0 while on my meter I would divide 1400 by 500 to get an EC = 2.8... way too high.

For the equal amounts of nutrients, my meter would have to read 1000PPM (EC of 2.0*500=1000PPM) The easiest measurement to give is EC as that requires no further exchange of information.

I know, it's clear as mud... 52.