Grow Mediums Questions about calcium and magnesium content

[greenjeans]

Working on getting my first grow rolling.. Seeds are about to break ground.

I am trying to get ahead of the game here.

First, I am growing Northern Lights auto in DWC, with cfls.

I have decided to use my tap water(don't try to talk me out of it. If it causes problems then I will learn my lessons the hard way). I have done research on my local tap water, and would like someone with some more extensive knowledge to tell me how the calcium and magnesium numbers look. I have spent all I am able to over the last few weeks, and need to do everything I can to not buy any more for a bit. Anyway, my tap water shows these numbers:

Calcium: 31-42ppm
Magnesium: 3-6ppm
TDS is 150-240ppm

Without really knowing where these numbers SHOULD be, the mag seems a bit low. I figure it will be easy enough to compensate, if I need to, with epsom salts.

What do you think of the "out of the tap" numbers? Keep in mind that my Nutrients do already contain some Calcium and Magnesium, which should boost these numbers at least a little..

I'm just starting out with all of this, and nutrient use seems a bit intimidating to me. My plan is to keep the levels really low at first, of course, and to be conservative with them throughout the grow. I will be using the manufacturer's charts, but I only plan to get things up to around half-strength unless I start feeling like they need it.

So school me. Help me with my tap water numbers so I can be prepared. Thanks in advance for whatever knowledge you can send my way.

GJ

 

[A4]

That looks fine bro, the more important question would be what is the EC of your tap water? I am sure there are more additives than just Ca & Mg. I would be more concerned about the overall amount of additives. Like you said though, it is what it is. If that is what you have to work with then that is it.

On the positive side, you want your Ca to Mg ratio to be 7:1. Yours is absolutely spot on!

 

[greenjeans]

I thought it might be helpful if I just put all of the numbers in here,,,
Bicarb 88-114
calcium 31-42
chloride 10-26
ph 7.7-8.3
magnesium 3-6
sodium 17-27
sulfate 22-36

 

[greenjeans]

That looks fine bro, the more important question would be what is the EC of your tap water? I am sure there are more additives than just Ca & Mg. I would be more concerned about the overall amount of additives. Like you said though, it is what it is. If that is what you have to work with then that is it.

On the positive side, you want your Ca to Mg ratio to be 7:1. Yours is absolutely spot on!

I added in all the numbers above. I'm not sure how TDS translates to EC, but the TDS number is 150-240ppm

 

[greenjeans]

If the EC is the same as the conductivity number it shows then it is listed at 264-360,

Conductivity-μmhos/m-264-360

 

[JAYAR]

off topic, but whats that pic on your avatar about?

 

[A4]

Yeah, that is quite high actually. The pH is quite high as well. Make sure you have a good sized bottle of pH down on hand because you are going to need it with the high pH and large amount of bicarbonate in the water. If it were me, I would get your water down to ~7.0 pH before I added my nutrients then check again.

Actually, with the water that high, I would probably put it in 5 gallon buckets and get the pH down and let it set a day or two and check again before using it. My guess is, you can get the pH down to 7.0 and check it the next day and it will be back up again. You may need to do it twice to get it corrected. If you don't, you will probably see some serious nutrient deficiencies about halfway through the grow due to pH swings.

Nothing that you can't overcome, using that water, so long as you know what to expect and what to do to correct it. Shouldn't be a problem but will keep a new grower on his/her toes.

 

[greenjeans]

I am on top of the PH. And you are right, it takes twice to get it stabilized.

 

[greenjeans]

off topic, but whats that pic on your avatar about?

It is a religious symbol. Like yours is! Google "Thelema".

 

[JAYAR]

i got mine cuz it looks badass lol im not an actual aztec, although my ancesters probably were! gonna google it now.