I have a 6 bucket rDWC setup circulating through a 14 gal. rez. There is 24 gallons total in the system. All of the water is being circulated by a 400 gph pump 24/7. Each bucket has 1, 6 inch air stone running in the bottom of it. Just yesterday I measured out my nutes and Properly adjusted the PH of my water to right around 5.8 for each 4 gallons I put in the system. Last night I discovered a small leak in my reservoir and had to isolate all of the buckets from my rez tub. Over night the PH of the water in each of my buckets had risen to about 6.2 (kind of scared me) Earlier today I fixed the leak and again properly adjusted the PH of the new 8 gallons of nutrient solution to about 5.0 to compensate for the rise in PH in each of my buckets (Im thinking the problem might lie in this step) I turned on the pump and opened all of the bucket lines and the water has been circulating now for about 4 hours. When i check the PH of the solution in my rez tub my meter (40$ Primo brand(?) model) will take a reading of about 5.9 in one corner, and a reading of about 6.1 in another corner. I originally attributed this to the drain line of each bucket draining into the different areas of my rez. It now seems, 4 hours later that all of my water should have circulated and mixed through my system more than thoroughly. My PH meter works perfectly fine because I have a small plant about 4 weeks old from seed in a smaller 1 gal DWC container and have been monitoring the PH of the small container constantly. The flow inside my tub also seems more than sufficient, all of my return lines enter at the bottom of my rez at one side and my pump is placed directly on the other side of the container ( about 1 foot away). What could be the cause of my erratic PH readings? Should I simply flush my rez? I know it sounds lazy but it is a pain in the ass even for just 24 gallons, plus more nutes, PH down and all of that good stuff. PEACE & LOVE
I should also mention that the PH is different in each bucket. Each of the 6 buckets has a PH of around 6.3 which is a bit high.... The water in my rez however is around 5.5 to 5.9 depending on where i take the reading. This makes absolutely no sense to me, the water is obviously being sent through my feed line and is being drained from each bucket via drain lines. the water is moving around in the system, no doubt about it. I will probably just end up changing out the water in the morning, though any advice is still very appreciated. PEACE & LOVE
I could not find any reference on the web to a Primo pH meter. I know they used to make one in the US but that was years ago. I don't have a whole lot of confidence with a $40 pH meter ..... Out of curiousity ... when was the last time the meter was calibrated? Anyway - with a cheap meter like that I would not be surprised that the accuracy of the meter is +/- 0.2 - which means that if your probe is in 5.8 solution a reading of 5.6. 5.7, 5.8, 5.9 and 6.0 are "reasonable".
So here we are 2 days later, Ive flushed my rez and added clean PH adjusted water and let it circulate over night. My readings still vary from corner to corner in my rez and also slightly from bucket to bucket. When I take a glass of water and get a PH reading from it it stabilizes. Should I just trust the stable reading in the glass? I know my PH meter is pretty cheap , its actually the $40 model by Hanna. But that doesn't account for the stable PH reading in my smaller 1 gallon container that seems pretty accurate considering the nice growth of the plant that is in it. In any other body of water it is capable of taking a stable measurement. The meter was calibrated about a month ago when i got it and it has been treated very well ever since. I really do not think the problem is my meter. If anybody has some expert advice on taking PH readings then please help out! PEACE & LOVE
Well I have a "well" pH meter so I don't do a lot of in situ measuring. However I do know that moving water can cause pH meters to fluctuate. How about taking a small sample from those areas that appear to have the most difference and measure that?
That is a good idea raoul and thank you for the quick reply, I will try that and share the results. As for the fluorescent lights there are none in my tent, just my 1000w mh in it's cooled hood. The Rez is probably a good 6 feet from the light. PEACE & LOVE
I have a recirculating DWC system. When I take the PH around the faster flowing water, the PH tends to be lower than if I were to test it in standing water. I believe the reason for this is because there is more oxygen present with moving water, causing the PH reading to be lower.
pH measures the ratio of H+ to OH- (and you thought water was H2O) More H+ the more acid More OH- the more base Now talk me through how movement messes with that ratio and Im a believer ... But I know I have seen it
That's very interesting mardukk, it seems like when I take a reading in a bucket which has an air stone in it, my ph reading is about a point higher than when I take a reading directly from the Rez or when I put water from the Rez in a glass and take a reading. Has anybody experienced this phenomenon in their systems? As for the moving water maybe affecting the PH, when I mix in my ph down and nutes into my bucket I constantly have the water moving and it gives me a stable reading each and every time. To me the movement of the water gives the reading a bit more reliability because the meter is taking a reading from different water molecules being circulated over it. So if the reading stays stable, that means your solution is consitent. That is just my line of logic. How many people take direct ph measurements with their meter directly in the Rez and how many people take a small sample from their Rez and test it in it's own container like a glass or something? Thank you for your replies everyone, I know we are on the verge of figuring this out. Any and all advice/input is very appreciated! PEACE & LOVE
yes... the problem was solved by mixing nutes in 5 gallon buckets... and then ph... let sit over night and then add to system once this program was implemented all ph swings stopped... in fact i almost never had to use ph up or down in my system... it was pretty nice the downside is that instead of adding water to my system i had to drain every week and start over.... I'd wanted to just add water to the system and with nutes and keep the concentration of nutrients higher... I'd gamble but the loss would be tremendous... so... ill stick with using more water good luck
Since the ph reading in both my Rez and buckets are different last night I decided to take water current and air bubbles completly out of the equation and start going solely on the samples taken with my glass. Last night I got the ph to 5.78 and just now when I checked it was at 5.9. My plants have also responded well as they has greened up a bit and have resumed growing. I'm hoping that measuring the ph in The glass is actually a reliable way of taking a reading and that the positive response from my plants and the water being in an acceptable ph range isn't just a coincidence and my ph is still actually off by a few points. However I still get slightly different readings from different areas in my Rez but the numbers aren't off by a dramatic amount, probably a variation of about 0.05 from location to location. This would go along with what tihspeed was saying by mixing up your nutes and ph and letting it sit over night. The water in my Rez seems a bit more stable so that suggestion seems very valid. It seems to me that taking a sample from my Rez and getting a reading from that is the most reliable way. Can anyone confirm/refute that thinking?
I think your right... if it helps any... the water movement always gave me unstable ph reading... I always remove a sample and test in a separate glass or container... edit.. i'd also have to imagine that the differences in ph are always going to be there, this would depend on how fast your nutes are being mixed via your bucket to bucket inline pump or air pump... so decide a good ph for your controller bucket and just stick to ph'ing a single bucket.. and accept that your never going to have a stable ph in every bucket...imo A friend of mine has the same setup.. he has a nicer pen... its a hanna that goes via cord to a hand help display... he had massive ph swings... i suggested doing what i was doing, mixing in 5 gallon buckets... he didn't really care for the idea of having 30 gallons of water sitting around all day... so what he does is use his res to mix his nutes and get stable ph readings then he opens up the ball valve and lets that bleed mix into his controller bucket... he always has nutes dropping into his controller bucket... I didn't think it was a wise idea at all and advised him against it.. but you cant argue with his results.. he still removes all water once a week and starts over... but he always has a fresh batch of nutes being mixed in a res with air stones.... its like lucas on crack i guess... I'd have to study the lucas more to know if thats part of its program.. but i dig his plants, their so huge... at any rate... im glad to see your getting results.... hope all goes well, keep us posted
I actually don't have a controller bucket, all six of my buckets are connected directly to my res, but the feed line and each of the drain lines has a ball valve right before they get to the Rez. Using your friends method of mixing up the nutes in the Rez I can close my valves; fill it up, get my numbers right and then open the valves, close, and repeat. My pump is 400 gph in a 24 gallon rez so it cycles all of the water around 16.67 times per hour, it's well mixed. I am going to continue using the sample method. Thank you so much for your help, I owe the improving health of my seedlings to you guys!
well then the only other option i would tell you to consider is getting a res that is the total gallons of all your buckets and get a controller installed... it will help and make things easier parts list: one Giant res(maybe 50 gallon bucket or so) one controller bucket(5 gallon bucket like the res of your plants) one adjustable float and a little pipe from the res to the controller bucket simple, cheap and effective... less work overall once installed good luck
Check the accuracy of your pH probe. Ive seen some units that are +/- 0.2 .. that means that 6.6, 6.7, 6.8, 6.9 and 7.0 are the same numbers! Don't expect them to be accurate to 0.02! Also - I didn't hear anything about a pump in your res to move the solutions around. How is your re-circ done?
I agree with Raoul there should always be a pump of some sort moving the solution around in the res. The bubbles in the buckets as well as the flowing solution should be enough for them but the res needs something as well.
The design of my rDWC is exactly the same as the one built by budslinger in his recalculating bubble bucket DIY thread. The 400 gph pump sits at the back of my rez and pumps water from the Rez into the feed line that constantly pumps water into each of my six buckets. Water then returns to the rez through gravity return lines at the bottom of my buckets. The water from the return lines enters my Rez at the front, so my water is constantly entering at the front, mixing in the Rez for a bit, then being sent back through the feed line. The water in my system is being cycled through at a rate of 16.67 times per hour, unless my math is incorrect, which it very well could be. I would think that this is enough circulation through my system to allow appropriate mixing of the solution. Though I could be wrong about that. Regardless, I have found that the sample PH reading taken from my rez and the PH reading taken from each bucket, is exactly the same. Though the PH reading taken directly in my rez is still inconsistent depending on the location. I'm pretty confident that my ph probe is quite accurate, though I probably will end up getting a better one. Mine has not steered my wrong yet so I have no reason to believe that it is working incorrectly. The health of my bagseed in my 1 gal mini setup is growing phenomenally. I have another question not exactly related to this one but since I have knowledgeable people looking at my thread I don't think it will be a big deal. I have a plant about a month old taking around 550 ppm of nutes. This plant is in a small 1 gallon miniture DWC container and is well ahead of the plants I have in my rDWC. The plants in the rDWC just got their first nutes of around 250 ppm. How would the induction of the older plant that normaly functions on a much higher nutrient concentration be affected by moving into a solution that is roughly half the concentration? Would it just cease to grow? Suffer some sort of shock? Should I just post this in another forum? Lol Whatever the case may be thank you everyone for your help! PEACE & LOVE
Moving plants around is never really a good idea unless you have to. The plant will maybe shock a little or slow with 50 percent less nutrients but if the light schedule is the same. It shouldn't be a problem. Keep is posted.
Hey - getting two identical readings at two different points in your system is great news. As to why the pH is bouncing about inside the res itself - I'm still of the mind that it's moving solution (quickly moving). Good news!