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pH Questions


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Old 05-07-2010, 05:09 PM
nodnarb22 nodnarb22 is offline
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Okay, so I'm new to this and i have a possibly very complex question. The pH of my tap water is around 10.0 the ec is around 400 µs. Im using a dwc/bubbler setup. Let me first say RO water is out of the question. Purchasing distilled water is almost out of the question for sure also. Now that that is out of the way. I'm using GH 3 part micro series of nutrients when freshly mixed into water it gives me around a 6.3 pH (i have a 1 gallon just of this that is almost 2 weeks old that is rather stable at that pH). I just prepped a new reservoir last night with 18 gallons of water and the accompanying nutes for a 1-1-1 mix for general purpose my pH was around 6.5 then also today when i checked it after letting it bubble for around 24 hrs my pH was up to 7.8 or so. Ive read that that happens when you apply bubbles to a volume of water by removing the co2. I picked up a small amount of sulfuric acid and have proceeded to used this to try and drop the pH. I have used what i would equate to A LOT around 60 ml of this and it only dropped the water to around 6.6 Ive given up on adjusting it down further today to allow it to sit and see if it doesn't drop more on its own. (their are no plants in this reservoir) The other tank that i have been using for 3 weeks has a high pH of around 8 but for whatever reason all but 1 set of plants in the container appear to be doing ok (but i doubt they really are). So my questions are, will "hydro designed" pH downs benefit me at all? I'm guessing my problem is the buffering capacity of my water is insanely high. Are there any other ways to remove/reduce or combat the pH level and the resulting buffering capacity?

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Old 05-07-2010, 07:10 PM
GpsFrontier GpsFrontier is offline
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A pH of 10.0 for tap water seems extremely high. I can't tell you what is in your tap water because it will vary everywhere. Your local water municipality may be able to shed some light on that for you. But assuming using a better water quality, even from an inexpensive charcoal filter or water from the $0.25 a gallon machines at the market (even for just a short period of time to see if it helps). Then tap is what you have to work with. There could be contaminates in the water that could affect the pH. I don't know how much chlorine might affect the pH, but you can let the water sit in an open container (with lots of water surface area) for 2 to 3 days and let the chlorine dissipate to see if that helps if there is a lot of it.

I don't know if you are using a pH test kit for hydroponics or not, but that would be my first recommendation. I use the pH drops from General Hydroponics, they only cost 7-8 bucks. Also I would use pH adjusters designed for hydroponics, anything else is likely to be quite unstable, and the more you need to add wont be good for your nutrient solution. I use the dry pH adjusting crystals from Earth Juice myself. They only cost about $9 (each up/down) for a one pound container, and they have lasted me over a year now. Adding bubbles to the nutrient solution wont change the pH. Your tap water itself does not have any buffers in it, that will be in the nutrients and pH adjusters (designed for hydroponics) to help stabilize the pH level.
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Old 05-07-2010, 07:54 PM
nodnarb22 nodnarb22 is offline
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I am using one of the MILWAKEE brand pH meters it is calibrated to 7.00 as that is all i had access to at the time. Cheap charcoal filter? you mean the Brita or pur type filters? Ive read that the "hydro specific" pH down seems to do soo much better and i was trying to confirm if this is correct or over stating the truth. Guess i will go to the semi local hydro store and buy some pH down, the problem is which one do i choose from i hear the AN ones are good but they dont carry they only carry the GH liquid and dry, Pro™ pH Down from hydro farm, and the TechnaFlora Down. I will wait to see what morning brings. Thanks for the info.
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Old 05-07-2010, 08:43 PM
GpsFrontier GpsFrontier is offline
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Quote:
I am using one of the MILWAKEE brand pH meters it is calibrated to 7.00 as that is all i had access to at the time.
I have never used a pH meter/pen but I believe that Milwakee makes them hydroponics and should be fine as long as it is calibrated (I have never needed to calibrate one).
Quote:
you mean the Brita or pur type filters?
I would suggest getting the best filter you can with your available funds. But yes, the Britta has a charcoal/carbon filter I believe, though it may take a while to filter the water you need from it because it's gravity fed. Even the filters that attach to the end of the facet would be better than straight tap, and you should be able to find them for about $20 and up. Just make sure it has a changeable filter, and they sell the replacement filters. If funds allow you can probably find a under the sink mount systems for $80 or so. These charcoal/carbon filtration systems will be able to remove most of the contaminates like calcium, lime and other minerals that can affect pH, as well as affecting the nutrient composition. Even herbicides that can be damaging to plants. As long as the filter is changed often enough.
Quote:
Ive read that the "hydro specific" pH down seems to do soo much better and i was trying to confirm if this is correct or over stating the truth. Guess i will go to the semi local hydro store and buy some pH down, the problem is which one do i choose from i hear the AN ones are good but they dont carry they only carry the GH liquid and dry, Pro™ pH Down from hydro farm, and the TechnaFlora Down.
I'm all for using alternate materials for hydroponics, but when it comes to nutrients and pH adjusters, I'll only use products designed for hydroponics. Unless I have an extra system to use and I don't really care about the plants, then I may experiment with other products. I have never used any other pH adjusters than what I mentioned so I can't compare them, but If I had to choose I would probably go with General Hydroponics products, simply because I can be sure and trust products made by them. I chose the dry crystals that I'm using because of cost. I think the dry product will last me longer than the liquid would (but I have never tried the liquids), I also had shipping costs to consider.
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Old 05-07-2010, 10:24 PM
nodnarb22 nodnarb22 is offline
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When i first got my pH pen and EC meter i did a little test of tap versus filtered ( i have a dupont 4 stage carbon type filter thats avialable at major stores, this one and all others all meet the same ANSI and NSF standards so their performance should be similar). and well their was little to no difference the ec is a little lower and the pH just .1 lower. When i got the meter it read 7.1 on a 7.00 calibration buffer that i KNOW to be accurate since we measure pH at my place of employment im going to let the samples sit overnight and see what change if any occurs. In the morning im going to experiment by putting a known amount of sulfuric acid in the samples and see if they both adjust equally to see if filtering is even worth this route, i will probably go to the semi local hydro store tomorrow and get some pH down from GH unless the shop owner can recommend something better (im hard to persuade so we will see) odds are i will bring home some sort of hydro specific pH down and will perform the same test on it to see if their is any better reaction to the pH down. as for the pH of tap water not changing from day to day i know this to NOT be true as i stated i measure pH at my place of employment well from one day to the next on the same source, ie same sink or hose, the pH can vary around .5 along with the chlorine in the water as we also test for free chlorine i can see a swing anywhere from .5 to 1.5 mg/L this can even vary .8mg/L on hot and cold water taps. im not claiming to know squat on pH or chlorine, those are just some observations ive made using some commercial grade testing equipment. my next step may just be to send my water in to be tested by the local water works.
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Old 05-08-2010, 01:34 AM
GpsFrontier GpsFrontier is offline
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Its not just the water, it's also the nutrients that you add to the water that over time that can react to whatever is in the water, and can continue to change the pH. Also the accumulation or build up of the minerals like calcium and lime in the system, that over the weeks that could make things worse. I don't check my pH daily of my water supply, but mine seems to change from time to time, at least the RO water. I figure this because I check the pH at every nutrient change, using the same amount of water and same amount of the same nutrients. Mostly I need to add a little pH up (lately anyway), but from time to time I need to add pH down instead. I never know witch it's going to be, so I check it first before adding either up or down (only after adding the nutrients of coarse).

I started out checking the pH every day to check for changes in my systems. Over time I got lazy with doing that, but if I add any significant amount of replacement water I need to check it again. I do try to check it every 3 to 4 days though, over time you can usually guess when it's likely to be out of range. I think you are doing good with your testing plan, that makes scene to me, though again that is just the water, and not taking into consideration any possible reactions with the nutrients. But I might also try retesting both samples every day, over say a weeks time and make note any changes.

I think your best bet is to use pH adjusters made for hydroponics as you said you were probably going to try. Though from here I have no idea what's in your water supply, so it's hard to give any advice there other than some sort of filtered water would be better than straight tap. I use RO because it was already installed in the house when we moved in, so I already had it to work with. Although I am looking into other options because the current system only puts out about a gallon per hour of RO. For the systems I have in mind for the future, that simply wont do.
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Last edited by GpsFrontier; 05-08-2010 at 02:17 AM.
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Old 05-08-2010, 04:43 PM
nodnarb22 nodnarb22 is offline
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Okay so i got a hold of some hydro designed pH down, this morning i used 25 drops of sulfuric acid just to drop the pH from 9.7 to 6.6 range, results were similar between filtered and non. Today when i got home with my GH pH down i put 10 ml of pH down into each gallon jug, the filtered dropped from 6.6 to 4.7, and the filtered dropped from 6.5 to 3.8, so yeah based on this information the GH pH down is quite effective at dropping pH, will have to be careful as i didn't get any pH up encase i overdo it.

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