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 yellownotepad
Pharmaceutical Agriculturalist
Registered: 06/22/08
Posts: 1,702
Last seen: 12 years, 5 months
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 my tap water - analysis and how to adjust for it 
#208399 - 03/24/09 05:04 PM (15 years, 7 months ago) |
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so i got my tds pen, and discovered i've got 580ppm tap. I looked up the most recent water quality report for my water district, and here's teh pertinent info:
Calcium ppm - 46
Magnesium ppm - 21
they state the average TDS for their water is 469, so my higher number may be a change on their part, or due to pipes in my house (the place is about 20 years old....is this likely?).
i'm trying to use lucas formula with my new ebb and flow table. for coir, i've had no problems with my tap water, but i don't have time for trial and error on teh new table. given teh ca/mg values, and the overall tds i'm showing, should i use gh flora hardwater micro, regular micro, or soem other solution? i actually started out using floranova for the table but when i got it home and tried to use it the stuff was way too sludgy and full of crystals for me to want to deal with (and yes i shook the crap out of it).
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yellownotepad
Pharmaceutical Agriculturalist
Registered: 06/22/08
Posts: 1,702
Last seen: 12 years, 5 months
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Re: my tap water - analysis and how to adjust for it [Re: yellownotepad]
#208402 - 03/24/09 05:09 PM (15 years, 7 months ago) |
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more info: according to gh if your calcium ppm is 30-50, they recommend a mix of hardwater micro and regular micro to accomodate. however they also say to use hardwater micro with tap water that is >200ppm TDS or >70ppm Ca. I have 580ppm TDS but only 46ppm Ca. Any expert advice would be awesome, i've been googling the crap out of this and haven't found an answer that makes me comfortable yet.
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 travelleler
New and used cannabis seeds!!!
Registered: 03/12/09
Posts: 121
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Re: my tap water - analysis and how to adjust for it [Re: yellownotepad]
#208421 - 03/24/09 05:32 PM (15 years, 7 months ago) |
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If I were you I'd err on the side of caution. But then, I'm not you. I always used RO water and added all the nutrients including calcium. Sort of a "from the ground up" approach. That way I have complete control of all the nutrients just by adding or changing out the res.
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Pour that on your granola and eat it, you zombie pinko bastards!"
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yellownotepad
Pharmaceutical Agriculturalist
Registered: 06/22/08
Posts: 1,702
Last seen: 12 years, 5 months
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Re: my tap water - analysis and how to adjust for it [Re: travelleler]
#208758 - 03/25/09 02:33 PM (15 years, 7 months ago) |
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alright well so far no answers, but i'm doing the math myself and posting here for others who may run into this sort of thing
the lucas formula's veg is 5ml micro and 10ml bloom, assuming 0ppm starting point (R/O water).
that yields this profile:
Nitrogen(n) - 62
Nitrogen(a) - 3
Nitrogen(u) - 0
Phosphorous - 62
Potassium - 100
Calcium - 67
Magnesium - 39
Sulfur - 52
Iron - 1.5
Manganese - 0.6
Zinc - 0.1
Copper - 0.1
Boron - 0
Molybdenum - 0.01
Cobalt - 0.01
a little more detail on my tap water, here's all the elements that i am factoring in here (all in ppm, except boron, which is parts per billion)
Calcium - 46
Boron - 140 ppB
Potassium - 3.9
Magnesium - 21
so based on these figures, if i mixed a lucas formula up using my tap but not checking on my water quality, i'd have 68.7% too much calcium, 3.9% too much potassium, 53.8% too much magnesium. The potassium is acceptable, and the boron is negligible. Everything else in the detailed water analysis is not listed in standard nutrient profiles, and so i'm leaving it out. The thing to see here is that while my tap water tastes normal, looks normal, and is generally good quality, it would most likely cause me some problems. However with that being said, I've been using my tap water in coir and it's worked great due to the way coir is.
So in order to adjust, if i were to switch to hardwater micro, and keep the same amounts, i'd have the following profile for the nutrients:
Nitrogen(n) - 48
Nitrogen(a) - 3
Nitrogen(u) - 13
Phosphorous - 62
Potassium - 100
Calcium - 71
Magnesium - 50
Sulfur - 52
Iron - 1.5
Manganese - 0.6
Zinc - 0.1
Copper - 0.1
Boron - 0
Molybdenum - 0.0240
Cobalt - 0
the changes with hardwater micro are that the overall nitrogen is raised by 2ppm (negligible 3.2% boost), but some is from urea which is absent in regular micro, cobalt is absent, calcium is reduced from 67 to 14 ppm (79.1% reduction).
If you take the profile where hardwater micro is used, and add in my particular tap water analysis, we can gather the following:
-my new calcium content is 60ppm. this is 7ppm (10.5%) less than ideal.
-my new nitrogen content is 64ppm. this is 2ppm (3.2%) more than ideal
-my new potassium content is 103.9ppm. this is 3.9ppm (3.9%) more than ideal
So we can see, using hardwater micro in the same ratio would make my overall nutrient profile much closer to ideal. It doesn't fix the overabundance of magnesium, but does reduce the calcium problem from being nearly 70% too much, to being 10% too little. I'm not sure how to deal with the extra magnesium, short of using a chemical process to precipitate it out.
If i wanted to be slightly more tricky, I could also use a combination of regular micro and hardwater micro to get the ideal calcium content (21 ppm from nutrients, 46ppm from the water).
The closest to ideal that I care to find right now is by using 1ml micro, 4ml hardwater micro, and 10ml bloom. That gets me to the following profile when my water's analysis is factored in:
Nitrogen(n) - 51
Nitrogen(a) - 3
Nitrogen(u) - 19
Phosphorous - 62
Potassium - 100
Calcium - 25
Magnesium - 39
Sulfur - 52
Iron - 1.5
Manganese - 0.6
Zinc - 0.1
Copper - 0.1
Boron - 0
Molybdenum - 0.01
Cobalt - 0
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Dr. Penguin
Registered: 05/19/08
Posts: 1,036
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Re: my tap water - analysis and how to adjust for it [Re: yellownotepad]
#209077 - 03/26/09 08:16 AM (15 years, 7 months ago) |
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Wow! Seems like you put some thought into this. My only concern is for the rest of the dissolved solids in your water. Where are they coming from if it isn't calcium? (which is generally the most abundant mineral in hard water) If your area uses an ion exchange water softening system you could have high levels of sodium in your water which would be far worse.
I thought my area was bad with 320ppm but 500 is bad news. I keep meaning to get myself an RO filter.
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yellownotepad
Pharmaceutical Agriculturalist
Registered: 06/22/08
Posts: 1,702
Last seen: 12 years, 5 months
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Re: my tap water - analysis and how to adjust for it [Re: Dr. Penguin]
#209093 - 03/26/09 10:58 AM (15 years, 7 months ago) |
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sodium is 83ppm. also keep in mind the water district states the water is 469ppm, so my higher reading most likely includes elements from the plumbing in my house i guess..?
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