Indoor Jack Herer Auto rDWC

I'll also raise the Ph a bit to try to hit more around 5.8 or so.
 
Thanks for all the input everyone!

So I was seeing the start of what looks to me like nutrient burn, some of the tips of new growth were starting to yellow, so I started topping up the rez with plain water (ph 5.5) instead of the 1/4 strength nute solution I have been using for top up. I ran with that for a week without it getting any worse and then on sunday when I did my weekly water changeout I mixed the nutrients at 20% less (just the AN M/G/B, i still kept the 1ml/L Cal-Mag I have been using). I noticed last night that since my rez change the symptoms are getting worse, now I am unsure if it is burn or possibly something else. I have noticed a bit of clawing and leave curling down a touch at the ends which I think would indicate over feed, but it doesnt make sense that symptoms are getting worse after decreasing the feed. I really need to get myself a TDS meter.
View attachment 1003998 View attachment 1003999
( Pics taken through a pair of blurple compensating sunglasses, haha)

Any thoughts?
Maybe too much Cal-mag? My water has around 60ppm Ca and 20ppm Mg according to the city water report and I have been adding additional Cal-Mag as it seems to help keep my water stable. I've read that the Ca in hard water is not able to be absorbed by plants very well and can actually decrease the available Ca that can be utilized? The other reason I've been adding it is one of my plants has been iron hungry it's whole life and the Calimagic I use has some chelated iron in it as well which that plant seems to really like.
I gotta get this under control before I have to leave for Texas, luckily the 6 pallets of equipment I shipped to Tx got held up in customs so my trip have been pushed back untill the shipment gets through.

From my limited experience I'd agree that's not nutrient burn. A very similar appearance occurred early in my last grow, at the time I think it was the pH.
 
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Yeah the 4.5-5.5 range with the drops is kinda hard to differentiate, its possible my Ph was on the low side. I picked up a bluelab Ph pen today to go with the TDS meter I got yesterday so that should help me figure out whats going on.
It's a little strange that only two of the tops on one plant are showing the symptoms but not the rest of the tops on that plant or any of the other plants, they aren't the closest ones to the light or anything either. I trimmed off a leaf to get a better picture:

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Last night I also decided to clean out and re-fill my storage tank where I had been keeping 1/4 strength solution for top ups. In the bottom of the tank was quite a bit of chocolate brown coloured precipitate:
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Any chemists in the house?
This is just what I wrang out of the circulation pumps little intake filter!

I was expecting to have some precipitate from the hardness in the water after bringing the Ph down but I was expecting to see white calcium carbonate not brown sediment. Typically I would think brown precipitation to be Iron of some form, but it is supposed to be chelated and shouldn't precipitate. I am guessing this has something to do with the above leaf problem. Anyone seen this before?
 
Could it be from the hydro stones? same kind of color possibly not rinse for long enough?
 
I prefer the drops. I recently tested the drops in buffer 4.01 and 6.86 and I also concluded that 4 and 5 are the same. The drops work best if you go for yellow, either slightly greenish yellow or slightly warmish yellow. I like to go for not less than 6 on hydro, most people recommend 5.8 but my experience is that 6.2 works better.

Organic nutrients like guano tend to leave a sludge like that. I would not think it's a problem.
 
The precipitate is accumulating in my top up tank, so no hydrotron, no roots, no light. It has a couple airstones and a pump that keeps the solution from settling out. I am running only synthetic nutrients (Advanced Nutrients 3part).
 
After much research I think the precipitate is likely Iron(III)Phosphate. Although it is severly taxing my knowledge of chemistry from my first year of engineering 20 years ago( before they kicked me out for being caught smoking weed on campus, ironic eh?). I will try emailing AN about it and see if they have any advice.
 
I called the Advanced Nutrient grow support line and explained the sediment I was seeing. They said it was probably the humic compounds that were settling out as they can only use particles greater than 50 microns for some reason. He didn't think it should cause a problem.
 
It's been a while since I posted an update,
I have been experimenting with different top up strategies trying to find a method that will make it easier for my wife to maintain the tent while I am out of town. My trip keeps getting delayed due to customs issues and weather problems with the equipment shipment.

My current system I am trying involved setting up a second 100L storage for fresh water. Now I have two 100L totes each with a sub pump to keep them stirred and aerobic, and valves to divert water to the control rez. The first tank I fill with filtered tap water and it has a couple airstones in it as well as the pump. I use this tank to adjust and stabilize the Ph of the water. I bring the Ph down over a couple days (after bringing the Ph down to 5, the next day it will be back up at 7, and I repeat a couple times until the Ph somewhat settles around 6.

I think this is the key to using hard water in hydro. You need to lower the Ph enough that most of the bicarbonates have converted to carbonic acid and then you need the airstones to strip the released CO2 from solution so the bicarbonates don't reform. It also prevents the Ca and Mg from being locked up in carbonates. At least that Is my understanding after a couple weeks of reading everything I could find about carbonate buffer systems. It seems to be working pretty well for me.

So my second tank holds mixed neutrient solution enough for both for the upcomming water change and for top up for the following two weeks. My plants are drinking 5+ litres of water each day so I mix 80L of solution the day before the rez change using the stabilized water from tank 1 and the scheduled nutes for two weeks. I make sure this stays stable for a day before draining the system and replacing 30L of solution (the system holds 40L but can only drain 80%). I then refill the fresh water tank.
During the next week or two I measure the EC everyday before topping up the water in the control rez. If the EC goes up from the previous day by more than 20ppm i top up with water from the fresh water tank and if the EC has gone down or stayed level I top up from the nutrient tank. This way my wife can maintain the system at optiumum levels by just taking one reading and turning on the appropriate valve to top off the level.

This system maintains a lower but steady concentration of nutrients in the system as opposed to the typical method of adding all the nutrients to the initial water change and topping up with only plain water. It will hopefully also let me stretch the water changes to two weeks while still providing fresh nutrients daily. Much less chance of nutrient burn as well.

So how is it working out you ask?
Well my plants have overtaken the halfway point in my tent and are putting on two or three inches of height a day and have been keeping me busy with defoliation to try to keep them under control.
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I appreciate your dedication but your last post made my head hurt. However I'm sure that as you progress down the track to master grower you will gradually simplify your procedure, in fact that's half the fun. I'm a minimalist kinda guy. btw they look tall for autos!
 
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