pH Drift, DTW, Flora Nova

[OG_TGR]

I haven't found any specific answers to my query in search so excuse me if I have overlooked them but I am experiencing a bit of trouble.

Set up specifics here:
https://www.icmag.com/ic/showthread.php?t=265307

I am getting considerable drift on a 55 gal res over a 18-24hr period. I will leave it @ 5.8-9 and the next day it will be at 6.0. I have been adjusting it daily with ~35ml of pH down at a mixture rate of 3t (1T/15ml)/250ml of water.
As of yesterday the shift was even higher, 5.9-6.2.
Today, I adjusted the pH to 5.9 and <12hrs later it was 6.3! I had to add ~85ml to get the ~50-54gal back down to 5.9.
Currently my TDS is ~590 (1.18ec).
I would greatly appreciate any suggestions. Please feel free to comment either here or on the actual set up thread. Thank you very much, in advance.

 

[westfalia]

A little drift happens as part of growing is my experience. going from 5.8 to 6.0 is no big deal to me. look at your plants; if they look good no worries

 

[watts]

use RO water or set up an automated doser that pumps pH down to desired set point. Or you could pH your reservoir to 5.0ish and let it climb

 

[Mister_D]

I agree with watts, adjust your ph to 5.5 then allow to drift up to 6-6.2 before adjusting back to 5.5 again. You will cause lockout problems by adjusting ph too often.

 

[OG_TGR]

Thanks everyone for your replies.
I could certainly set up a dosing pump, or adjust down and let it drift back up to the right point but doesn't it seem a bit like treating the symptom?
I just figure, adding that much pH adjuster every day has to have some negative effects in the long run. I may not see them now but I am concerned about long term, cumulative effects. Everything seems to be doing fine, and I am currently only watering 2x/Day, one for 3 minutes (to run off) and the other for 1 minute, 7 hrs later.
It's strange how relatively rock solid the pH is with these nutes when you are running twice the strength, as in the recirculating schedule, but yet so unstable at half that strength, for the DTW schedule.
My tap water is pretty good, always <100 ppm and a constant 7-6.9 pH. I've ran a RO before and considered doing it again, just to have a "perfect" baseline but it would seem that in this case that would actually remove the buffers that are already added to the tap water. Unless the drift is in fact due to a reaction to some trace that is in the tap water.

Again, thank you all for your input. Hopefully I can return the favor someday!

 

[watts]

i believe the buffers in the tap water is why it's rising.

 

[OG_TGR]

i believe the buffers in the tap water is why it's rising.

Ahhhhh, I didn't think about it that way. I was thinking just "buffer" as in, keeps it at any set pH, as opposed to pH specific buffers. Excellent point.
Oddly enough, I am finding that now that the res is about half empty (half full?, haha), the pH seems to be more stable. Strange.
I know in the past I have used buffers meant for aquariums, but most are in fact pH specific, and living fish don't normally take to 5.8 very well!
(So now I'm strongly fighting my tendency to be easily distracted; stay on task and not spend hours looking into why Aquaponics works, then, lol)

 

[OG_TGR]

I am considering buying Discus buffer (5.8-6.0, perfect!) in the interim. I, of course, will research the contents and make sure there aren't any nasties in there (cure worse than the ailment? No thanks!).

http://www.seachem.com/Products/product_pages/DiscusBuffer.html

I am shopping for a new R/O, as well.

 

[MagniKhan]

I agree with watts, adjust your ph to 5.5 then allow to drift up to 6-6.2 before adjusting back to 5.5 again. You will cause lockout problems by adjusting ph too often.

I think the nugget of wisdom is here.
I my studies of Lucas, Lessismore, Rumpleforskin, Elvme2, etc., they all recommended this method.
Over all I usually set my rez at 5.5 in the AM and by the afternoon she has risen to around 5.9. It's a 35 gal barrel that I use for my DTW system.
When I used ebb&flow I would set it at 5.5 and let it rise for a few days till it got to around 5.8-5.9 and the lower it. In the last two or so weeks I keep the ph on the low side as she looking for nutes that are more available there then high.

 

[OG_TGR]

I think the nugget of wisdom is here.
I my studies of Lucas, Lessismore, Rumpleforskin, Elvme2, etc., they all recommended this method.
Over all I usually set my rez at 5.5 in the AM and by the afternoon she has risen to around 5.9. It's a 35 gal barrel that I use for my DTW system.
When I used ebb&flow I would set it at 5.5 and let it rise for a few days till it got to around 5.8-5.9 and the lower it. In the last two or so weeks I keep the ph on the low side as she looking for nutes that are more available there then high.

Thanks for the input. I have been specifically considering adjusting pH lower towards the end for this very reason.
I am going to try the buffer today to see what happens. I can adjust everyday, but that just seems counterproductive to me in the sense that I would like the system to be as completely autonomous as possible to not only eliminate potential mistakes from the "human factor" but also ease maintenance. Also, with the rates at which I am having to add pH adjuster there has GOT to be some peripheral effects to the system that have yet to become apparent. In my experience, cumulative problems also seem to be the hardest to remedy!

All in all @100ml/day I would consume an entire 1.5lb container in probably 6 weeks.

 

[OG_TGR]

Note: Added the Seachem Discus buffer at recommended minimum dosage (~2.5t for ~50-53 gallsons) and pH is dead on at 5.899 without further adjustment.
Something I forgot about that would be nice about using the buffer as opposed to R/O is the amount of water that would not be wasted in the process. I think that was one of the factors in me deciding to forgo it this time, as opposed to times before.

 

[MagniKhan]

Note: Added the Seachem Discus buffer at recommended minimum dosage (~2.5t for ~50-53 gallsons) and pH is dead on at 5.899 without further adjustment.
Something I forgot about that would be nice about using the buffer as opposed to R/O is the amount of water that would not be wasted in the process. I think that was one of the factors in me deciding to forgo it this time, as opposed to times before.

I have a decent RO filter that I purchased, I used for everything...then I realized it was a needless pain in the ass and only use to flush and for spraying clones.
My tap water is about 220-230 ppm and has clormine in it, works great. When you figure your ppm for your nutes just minus that number (test your tap water to get the number to minus). Since I grow in coco it keeps me from having to spike it with mag/cal ( though I do once and while anyway )

 

[MagniKhan]

Also if you are worried about chlorine or chlorine, don't, your growing hydroponically. You provide everything your girls need.
I like the way Krunchbubble ( if you haven't read his post and threads I highly suggest you do, though large scale, there is all kinds of wisdom and knowledge to be had) put about what he thought about chlorine killing microbes in his rez, he said something to the effect of "good, I go hydroponically and I don't want shit growing in my rez......", it should be a dead rez.

 

[OG_TGR]

I agree with the concept of positive benefits of low levels of chlorine. Besides, chlorine evaporates from open containers in <8 hrs anyway. I know some people need to have RO due to poor quality of tap water but as it happens the tap water where I am at comes out as some of the best in the country.
I'll check out the threads you are referring to, thanks!

 

[watts]

Don't you have to keep applying the seachem daily for a while? I don't know if it's optimal for our needs, since we change out reservoirs often.

 

[OG_TGR]

Nah, you just add it to the res for the volume that is available, and it should stabilize rather quickly. After that it's just every res change (weekly for me).
The buffer was $10/250g. Considering a tsp is ~ 5g and each change takes 12.5g, that means one container should theoretically get me through two whole bloom cycles. Most importantly, if it keeps me from absolutely having to attend to it every day, I am sold!
So far today it looks good, I'm about to check it again soon. Of course I don't want to eliminate drift entirely, but rather slow it down. I would still rather have it almost completely stationary as opposed to the rapid shift I was seeing.

 

[OG_TGR]

Today it moved just a tad to 6.0. I was curious so I adjusted it and it only took 10ml of down to get it back in 5.9 range. Now, in the future I will likely just leave it alone and let it run at 6.0 and then adjust it when it, theoretically, will drift up to 6.1 after a few days. Who knows, maybe it will just stay dead on at 6.0? Either way, there is a lot less additives going into the res!

 

[OG_TGR]

Ok I think I have tracked down the culprit. I have run two systems, almost identical, and one was showing relatively stable pH as opposed to the newer one, outlined here, with the significant pH drift over short periods of time.
It appears that what was causing or at least CONTRIBUTING to the pH drift was exposing the nutrient solution to indirect HID light. The system with the high drift rate is using a white, polypropylene 55g drum for a reservoir. The top lip of reservoir is about 3' (~1m) from a 600w HPS. While the reservoir isn't transparent, it isn't entirely opaque, either. I have wrapped the reservoir in panda plastic (black inside, white out) and I have yet to see any drift in two days.
Now, I did use the pH buffer as well but it has been diluted to 25% original dosage. At full strength I still was seeing minor drift (.06-.16/36hrs), but have yet to see this at this low concentration. At next res change, I will not use the buffer at all and see what happens.

[The other system w/o pH drift issues was in heavy duty black PP tubs with semi-opaque, yellow lids]

 

[InjectTruth]

The original reservoir strategy I learned from pH was to dump and replace as you described, once an equal volume of addback water has reached. IOW, when a 20 gallon res, got 20 gallons of top up water, the res was dumped and refilled at fresh 0-8-16. This was not with pH adjusted water, because it works best to allow the res pH to fluctuate within a range of 5.3 to 6.3

An alternate reservoir management strategy I now prefer, is to add nutes to the reservoir in the addback water. The goal is to bring the reservoir back up to 1300ppm. In this strategy, I feel a single res change at harvest is sufficient.

Despite the obvious concern that this non dumping approach allows toxins to build up, I never experienced toxin buildup. this surprised me and caused me to alter my thinking about plant metabolism. It seems they do not excrete toxins the way organisms with digestive tracts do.

How much nutes goes in the addback water varies by res to light ratio. For example, a 50 gallon res under a single 1k can be topped with 33% of 0-8-16, and the 1300 tds will be approximately achieved... Im not a stickler for that number, and am happy fluctuating anywhere between 1100 and 1500ppm over the course of a week, such that if one chooses to top only with water for a few days, the nuteing can be done in a single session each week.

If the same 50 gallon res is used under twice as much light, it will probably require twice as much nutes in the addback water.

The most primary concern is to achieve the TDS increase, while staying within pH range

adding nutes lowers pH, so sometimes one can avoid pH adjusting, by adding more or less nutes
adding water raises pH, so dont adjust a reservoir, until it is topped up with water and nutes

http://www.cannabis-world.org/cw/showpost.php?p=9606&postcount=4

 

[InjectTruth]