another nutrient question

20 years ago

Hi, I am using an off the shelf liquid plant food in my new pipe system.. This product is using urea as the major source of nitrogen. Because the urea will not undergo any microbial action in my 100% Perlite medium, I understand that the urea nitrogen componet of the plant food concentrate will not be converted to a useful form that my plants can use. Assuming that all the other components are useful , I have been using liquid calcium nitrate to supply the nitrogen. My question is related to determining the correct ammount to add. If my plants like a total TDS of 950 ppm, but the recommended level of nitrogen is listed as 400 ppm, I have assumed to this point that a workable procedure might be as follows. My tap water reads around 420 on my meter. I have added enough of the off the shelf plant food to bring the reading up to around 750, and enough calcium nitrate to bring the reading up to around 950. The balance of the off the shelf product is 10-10-10. With out the nitrogen it would seem to be 0-10-10 until I mix in the calcium nitrate. However, To what degree of conductance the various elements of the mix might have is somewhat confusing. If I need the nitrogen component to be 400ppm, perhaps I should add the calcium nitrate first to raise the overall ppm of the tap water to around 820 and then add the off the shelf product to bring the overall level to the desired 950. So far, my plants seem to be happy and growing well after several days of this mis-treatment. The reason for all the above mixing is to save time and money as the off the shelf liquid plant food is cheap. The liquid calcium nitrates is also low priced. At least it seems inexpensive, The total amount of nutrient I can make up is probably 100 gallons for around $10 dollars (for a level of around 1000 ppm). How close to retaining the 10-10-10 level is unknown, and questionable. I have read some other postings where people are buying many different ingredients and using digital gram scales, or the retorts like "go take a chemistry class". That's fair, but just by chance, maybe someone here on the hydro forum might have worked through something simular in the past, and may care to share their expirence. Thanks, chuck

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Comments (6)

chuck
Original Author
20 years ago
I received a direct email concerning my question. It turns out that the electronic meter I am using measures the ability of the nutrient and water mixture to conduct current, and has nothing to do with ppm. If I were to dilute the calcium nitrate in distilled water, the meter might be used if it were first calibrated to a known standard. The meter is useful if the nutrient is of a known ratio of desired minerals and the reading on the meter is reflecting the changing degree of conductivity which increases in close porportion to the ratio of nutrient added to water. This might be easier if you start with distilled water which would have no conductivity of it's own. When using tap water, it becomes kind of complicated. I may call my city water department and request a recent analysis. I guess that it's either trial and error or the digital scale. Somehow, my plants are still hanging in there.
baci
20 years ago
Thanks for posting the info. It adds substance to the forum & will help others with the same question.
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jimr007
20 years ago
Hi Chuck,
Please have a look at my web site in Australia. It will give you quite a few tips on hydroponics.
http://www.home.aone.net.au/hydroponics

jimr007
Australia.

Here is a link that might be useful: Simple Sand Hydroponics
chuck
Original Author
20 years ago
Thank you Jim, your website is very nice, and the information is just what I was looking for. I hope that others will follow your link. They will find great information presented in a nice way. I once met a band called the leaping lizards from Australia. Great bunch of guys. That was years ago. They were representing Fosters. chuck
jimr007
20 years ago
Hi Chuck,
With regards to conductivity meters, I have tried to correlate total dissolved solids (tds) to conductivity, and gave it away. I just use a pH meter to measure and adjust the pH at the end of each day. At the end of the first and second weeks, I give the system one more dose of nutrient solution, and at the end of the third week, I drain the nutrient out and do a complete wash-out with fresh water.
After that is drained out, I refill with fresh nutrient solution and start all over again. Using this method, I do not bother with conductivity ... and retain my sanity at the same time.
Jimr007
Australia.

Here is a link that might be useful: Simple Sand Hydroponics
jimr007
20 years ago
Hi Chuck,
I looked up the Leaping Lizards on the Internet. They were variously known as the Leaping Lizards Bush Band, and the Leaping Lizards Celtic Bush Band, and were at one time based near the Gold Coast (1 hour by car south of Brisbane, Queensland.)
I could not find a web site for them, but found about 2 pages of entries (some dead links) on Google.
I am unable to determine whether they are still playing as a band or not.
Fosters, of course, is still a very popular Australian made beer.
Sorry, I cannot be more specific about the Leaping Lizards.
Cheers,
Jimr007
Australia.