[TheGreenMachine]

I keep getting mystery PH drop for what appears to be no obvious reason.

Since about a week flipping into flower I've had fun and games with the PH in my aquafarm. In veg it was perfectly stable but as soon as I put her under the big 600 lamp, she started to act strange.
She's been eating and drinking just fine for the most part but some days the PH will just drop or that's how it seems because I can't find a valid reason for to explain it.

It doesn't appear to be anything I'm doing as I'm not doing anything different from day to day that I can think of.

The most obvious thing that came to mind is root rot but about 2 weeks back I lifted the basket out to inspect the roots and they looked perfectly healthy. White, no bad smells in the rest etc. All looked good.

As stated, the problem first appeared after flipping into flower. It went on for about a week then I managed to get it stable-ish again. It seems the plant loves being at aroun PH 5.9 - 6.0 the best as that's where it stays the most stable.
I also extended the time between res changes from 7 to 10 days to maintain stability. All of this was working pretty well until about 2 days ago where she's decided she's gonna start dropping again.

 

I normally set my EC at around 1.55 - 1.6 and she's been quite happy at that. I'll go in in the morning and she'll have drunk about 6 - 8 liters but the EC will be close to where I set it the night before meaning to me she's eating and drinking equally. The past two days I've been going in and the PH has crashed to below 5 and the EC is slightly higher than was set. Yesterday the PH had dropped from 6.0 down to 4.2 and the EC was at 1.65 and she'd only drank half the usual amount. This morning she was down to PH 4.2 and an EC of 1.7 so she's eating less.

All I've been doing the past two days is topping up with tap water that's been stood and airated for 24+ hours to dilute the EC back down and to raise the PH with the addition of silicone.

 

 

The plant itself looks extremely healthy but I just can't find any logical reason as to why the PH would drop like this but have periods of stabilty inbetween. I have never known anything like this.
I've had rot before in the past when I've done hydro before but it wasn't like this. It was all over the place but this plant isn't behaving like it's got bad rot.

 

 

Apart from 3 days this month when we had exceptionally warm days, the rest temp has spent the most part at between 16 and 19C.

 

 

I did at one point wonder if I was compounding the problem by adding silicone.... By that I mean did I add enough and give it time to settle or has it settled over 12 hours and I'd not used enough? Has the plant eaten what silicone I've put in that quick the PH has dropped again?
 

 

I've never seen a problem like this before and I'm utterly stumped by it. For the last 2 weeks it's been pretty stable and now it's eating less, the PH is dropping but she's drinking.


I'm going to dump and change the res tonight as a matter of course and I'll set the EC down to around 1.4 - 1.5 and see if she starts eating as healthly as she was.

 

I am wondering still though.... Hypothetically speaking, if I made up a solution and then added 1ml silicone per liter and then used PH down to bring the PH back in range, is it possible that the plants can eat all the silicone and in so doing they remove the PH UP effect it's having and causing the PH to drop in sympathy?

 

As of now, I'm at a loss. This has to be THE most finicky plant I've ever worked with.
 

 

 

 

Edited by TheGreenMachine, 17 May 2016 - 06:12 AM.

[2scoops]

Generally EC climbing and PH dropping is down to slightly overfeeding, growing in water an overall EC of 1.2 to 1.6 is more than enough depending on whether your hard or soft water, silicon is sound dont worry about that so long as it isn`t clouding your ferts up so they not binding together properly your cool, silicon should stabilise PH if anything, but also small rezz can play havoc with PH it`s alot harder to keep it set and stable than if using a larger rezz, changing out fresh every few weeks is the way to go in that case and should help out a wee bit more. Here`s a good readtelling you what`s what when you getting PH movement http://www.t-g-c.nl/...ts-telling-you/ Id try an oberall EC of 1.4 and even lower of your softwater.

[TheGreenMachine]

Hey Jimmi.

Thanks for the advice mate.

I'm in hard water and the res size should be 35L without root mass in there.

 

After I posted this yesterday I got straight on to making up a bin of fresh nutes for a res change today. I initially set the bin of nutes to EC 1.5 and PH 6.0 ish and I let it bubble and settle out for 24 hours.
Having read your reply I've knocked the EC back to 1.4 as per your recommendation. I actually overshot diluting down the bin of nutes and it's at 1.35 but that'll do.

 

I've now changed the plant's res and she's in fresh nutes at EC 1.35 and PH 6.1 - I've set the PH a little higher just incase she decides to drop again.

She's definitely objecting to something because this morning she was back at PH 4.2 and EC near 1.75 so she's rejecting the feed now for sure. Still drinking though and no signs of major overfert / burn etc.
Still looking green and healthy.

 

Hopefully It's just a case of I've been keeping them right on their feed limit at 1.6 - 1.65. I was just going by the water level dropping and for the most part the EC staying the same.
But I guess if I've been feeding her right close to the limit, any problems would be immediately obvious. I.e. no room / margin for error.

She's on nothing but Canna Aqua Flores A and B with 1 - 2 ml of Canna PK 13/14. No other additives other than the bennies. Per 35L I usually use 30 - 40Ml of A and B each and literally a 2ml squirt of PK which will take the EC to about 1.5 from a starting EC (tap water) of around 0.6. I'm 5 weeks in now so I'm looking to start backing off the A and B a little bit and replacing with more and more PK up until week 7. Gradually introducing it until I'm at max strength by week 7. Or that's the plan. Right now it doesn't seem like she needs it. So I may leave the PK off altoghther. I really can't make up my mind whether it's worth using it or not when the Canna A & B seem to be doing a reasonable job.


 

Edited by TheGreenMachine, 18 May 2016 - 06:20 PM.

[TheGreenMachine]

Jimmi your advice seems to have done the trick. I couldn't wait til this evening so I snook in with a green light to check the readings.

Having set the EC to 1.35 and the PH to 6.1 yesterday I was pleased to see my girl had drank near on 6 liters and the EC was down to 1.27 - 1.28 and the PH was UP to 6.2
I'm going to keep her at around 1.35 - 1.4 as you suggested from now on and not push her so hard.

 

Many thanks for the top advice mate!

[2scoops]

Jimmi your advice seems to have done the trick. I couldn't wait til this evening so I snook in with a green light to check the readings.

Having set the EC to 1.35 and the PH to 6.1 yesterday I was pleased to see my girl had drank near on 6 liters and the EC was down to 1.27 - 1.28 and the PH was UP to 6.2
I'm going to keep her at around 1.35 - 1.4 as you suggested from now on and not push her so hard.

 

Many thanks for the top advice mate!

 

You were just overfeeding a little bit is all by sounds of it, so basically when you dip it and its climbing then just drop the EC a wee bit is all, you want it so when you dip the rezz daily it`s staying the same or just dropping a wee bit and also go by how the plant is looking, if that looks ok your good to go, but as said previuosly changing the rezz regular helps too. But sound as a pound m8.

[TheGreenMachine]

Bit of a dodgy day yesterday. Not sure what to make of it.

The first day I knocked the EC back as suggested she responded well. The next day I could see she had clearly eaten a lot and the PH was rising.

Yesterday though she'd drank almost 7 liters but the PH had dropped from 6.1 down to 5.7 and the EC was up from 1.35 to 1.37.
Last night I reset the PH to 6.0 using plain water and this allowed me to also lower the EC slightly lower to 1.31.

I've not checked today yet but I fear I'm in for more of the same.

One thing I can rule out is not allowing the nutes time to stand and the buffers to work etc as I mix up in 50L bins and let it all stand, stabilise, airate etc for 24 hours min before use. I've stopped using silicon in the flowering plant altoghether to raise PH and instead only use tap water that's also been stood and airated for 24 hours minimum.










 

[2scoops]

I wouldn`t mess with resetting too much if its hanging around and between 5.5 and 6.2 your cool and as high as 6.5 at a push,if it`s only moving slightly then just reset it every time you fill the 35litre rezz which to my reckoning should be every 3 to 4 days, then the plant will drink and eat whats in the rezz, so when you do refill and add ferts they will be just about tip top and in said ratios as on bottle were as topping it up everyday well the plant maybe picking at ferts and say maybe taking more N than others so overtime the said rezz N.P.K ratios wont be as on bottle so in the case i just said theirs alot less N in feeds, which is another reason for changing the smaller rezz every few weeks, that`s my take on it anyhow. But yes letting PH drift up and down inbetween said range it`s pretty much ok and i can`t see a problem with that.

[TheGreenMachine]

Cheers Jimmi.

I must be getting too fixated with the idea that the EC must go down and the PH must go up.

So when you say fill the res every 3 to 4 days do you mean leave it 3 - 4 days between topping it off rather than topping off every day or do you mean dump the res and add a fresh lot every 3 - 4 days?

At the minute, I top up every 24 hours and change the res every 7 - 10 days but that's because she drinks loads. 2 - 3 days between top offs and I reckon she'd be near dry.

While the res is 35L, it doesn't hold that amount now due to the huge root mass dominating the res. It's probably more like 20 - 25 liters after the root mass displacement.
In 24 hours she can drink 7 - 8 liters and that drops the waterlevel to around half way down the tube at the front of the farm.

When I got the farm I marked off 35L on the clear tube at the front and then marked off to the level which takes it to the bottom of the pot / basket. If I fill to the level of the basket, it's about half gone by morning which indicates how much of the space the roots are taking up. Mental lol



Cheers.

 

[wah wah]

I mix a 40ltr nute batch up ec,,ph it...leave overnight..then just top-up...i used to change rezez at least once a week in veg...an twice a week when in flower...what a waste of nutes...unless there,s any probs i don,t change full rez all through grow..also i think aquafarm rez holds 20ltr of water/nutes..an 15ltr of pebbles..mine do anyway.

[TheGreenMachine]

And the PH today..... 3.8! and the EC is at 1.45.
 

This is what happened before. The PH would just fall to silly low levels overnight. Then it stabilises for a while then it'll crash again. This is the worse crash by far though. From 6 down to 3.8. Something isn't right in there



 

Edited by TheGreenMachine, 21 May 2016 - 05:56 PM.