First Post - Cal deficiency or root rot or other issue

Hi everyone. Long time lurker but First time poster here, inevitable asking for help. Will likely be a rather long post.

So, on my second grow with 6 G13 labs feminised pineapple express from seed. Flowering under 1000w HPS, in a 1.2x1.2m flood and drain table using hydrocorn pebbles, started in rockwool cubes. In week 5 of flower. Feeding GHE 3 part, plus pro bloom additive. Currently at 2.0 EC. Was holding PH around 5.8, but moved to 6.2-6.5 now in case of cal issue.

Getting yellow, crisping to brown leaves as shown in pics. Have read alot and kind of looks like calcium deficiency, but concerned could also be root rot (or even light burn) Saw a much smaller amount at end of previous grow, but was during flush so wasn't too concerned. My table was being flooded for 10 mins, 6 times/day during 12 hour light period. Not floods at night. The ph is generally stable in my reservoir, but there have been one or two swings downwards recently that seem to correlate with when more damage appears on leaves.

So my questions. Should I add a calmag supplement (I have some on the way) to my feed? I'm using the soft water terra aquatica (ghe) line and they don't recommend it.

If its a ph issue, does anyone have any suggestions what causes the sudden swings? It seems stable for 2-3 days then can move 0.5-1.0 ph overnight.

I've dropped my floods to 5 x 10 mins /day. Should I move to 4? If it is a root rot issue, would a dry day help?

I've ordered some hydrogen peroxide. Is supplementing my reservoir with this a good idea to combat any root rot in this case, or as a preventative anyway?

Am I totally barking up the wrong tree and is it a light burn issue? In the pics I've included the sativa dom looking pheno (its drooping leaves are making me suspect overwatering) which is also showing some signs of foxtailing. I got a fair bit of foxtail on my previous crop of skunk #1, but that grew through a heatwave with insane grow room temps.

Anyway. Thanks in advance for any advice. I've done loads of reading and convinced myself me plants have all sorts of issues. Hopefully they'll be good come harvest. The actual buds all still look relatively healthy at least

A bit more info in case it helps with any advice. Grow room temps are fairly stable around 25C lights on, 18C lights off. Relative humidity is held at 50%. The issues seem to be mostly showing on the indica dominant phenos that look further along in their development. The stretchy sativa leaning pheno looks much less stressed, just some drooping leaves and mild foxtail on the higher up buds. The reservoir is roughly 100 litres and contains 2 airstones running 24/7. Air circulation in the room should be very good as I have a total of 5 air movement fans in there, plus an intake and exhaust.

Wondering if I should have posted in the hydroponics section for specialist advice?

Remove the bloom additives and see,dropping ph indicates root problems or over feed. Does your EC drop after a few days? If yes then their eating. Light burn, no dont see any. Magnesium deficiency possible.

A dry day isnt a good idea,floods need to keep things wet any dry back will create salt build up indicated by a spike in EC.

Always a good idea to feed low at the start,wait and see.

Better pics also,blurry when i zoom in.

Thanks for the info Myke. The pro bloom additive is actually an addition since I saw the problems, added as TA claim it aids calcium absorption. I will try leaving it out and dropping the EC slightly. Up to this point I've pretty gradually increased the EC, most of the time it drops slowly / stays stable. Similarly to the PH though, the largest swings seem to occur quickly and correspond with when the leaf damage turns up. This is leading me towards the root issue. If you, or anyone else have any experience with hydrogen peroxide (or anything else) as a treatment I'd much appreciate hearing about it.

Also, if mag might be an issue. Does anyone know anything about adding mag to the GHE 3part range for softwater? Their website doesn't recommend it, but doesn't say why. Is it harmless, or would I be better off using more of the micro in my mix instead?

Apologies for the picture quality, fans blowing everything around. I'll take some more and repost after 7pm when their dark period is over.

EC of 2. Crispy leaves. Hmmmm. I wonder why? You say this is the second time you've grown or the second time running this strain and setup?

Second time I've grown total. Grew skunk #1 last time and saw a very similar, albeit smaller, issue but just during the last two weeks after feed was tapered off. This, as well as the way the discolouration started as small spots in the middle of leaves not at the edges, led me to believe it probably wasn't nute burn. It started at a much lower EC too. Happy to be corrected though if its most likely nute burn.

I've attached a few more close up pics, hopefully a bit more helpful. Still a bit blurry when zoomed but I must either have a rubbish phone camera or a terribly unsteady hand because all fans were off this time.

Your flushing with straight water every week or two for 24 hrs? What is your water?

I haven't been flushing that much. You might have identified the problem. I normally do one flood cycle of plain water every 2-3 weeks at most. Thinking out loud, would the lack of flushing have allowed too much salt build up in the medium, especially given repeated rapid evaporation, which may have in turn damaged the roots / inhibited nutrient uptake? I'll flush tonight and increase my flushing frequency anyway.

I have the GHE flush agent product. I only use it normally when I'm cleaning out the hydroton prior to use (its so full of crap when delivered). Would that be a useful addition now too or is it a bit of an unnecessary gamble?

I use tap water in my system. Its relatively good in my area. Has a ppm of around 100 and a ph near enough 7.0.

Drain,fill with water, turn pump on for continuous flow if your system can do that.Say 3 hours,drain fill again let system run for a day.Check EC should be close to tap if not flush again.

100ppm water so some calcium in it.I have a little harder at 170 ish.

So can I leave the roots fully submerged for 3 hours?

Hand pour water through your rockwool also or net pots whatever you have.

Hydrohobby said:

So can I leave the roots fully submerged for 3 hours?

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Not sure what your system is? Straight from the tap then pump out to waste works too. Not ice cold though lol.

If water is flowing its ok stagnant water is no good.

On it, cheers. I'll let you know how things go

myke said:

Not sure what your system is? Straight from the tap then pump out to waste works too. Not ice cold though lol.

If water is flowing its ok stagnant water is no good.

Click to expand...

Its a recirculating flood and drain, in hydroton pebbles. If I leave the pump on the water will be circulating with the table filled to the drain level. So not stagnant, but definitely submerged. Maybe I'll do like an hour continuous then the usual 5 floods for the day. Will mean I get to bed at a reasonable time

I think its root rot. Fast PH drops are usually root rot.

It doesn't look like you're running anything to combat bad bacteria. You can either run a sterile system (h202, bleach, etc) or a live system (beneficial bacteria like HydroGuard, but Southern AG seems popular around here and I will likely try it next since it's cheaper and more concentrated from what I understand).

Research and see the pros and cons of each system. Note that some nutrients can't be used in a sterile system and that adding H202 to a live system will kill any and all bacteria (good and bad ones).

Edit: The below is for 3% H202, do not use this ratio with a higher concentration of H202!
To treat root rot you can add 15ml of H202 per gallon of reservoir water and then flood as normal. I'd start with 10-12ml per gallon and increase to 15ml after a day or two as long as the plants seem OK. Note that H202 dissolves at a rate of 25% per day. I add H202 every other day at 50%. Once the root rot is gone you can back down to 5ml per gallon if you want to continue running H202. Or after 4 days you can start using beneficial bacteria.

Thanks for the reply ThisBud. The root rot does seem likely from what I've read too. And you're right, I don't have anything combating the bad bacteria. I've got the flush going now, because as Myke pointed out I dont think I've been doing it often enough anyway. I ordered a H2O2 product the other night, being delivered tomorrow. Its liquid oxygen from growth technologies, 11.9%. So bit under half the dosage strength you've recommended should be good? Ill do the proper maths with the ratio in the morning so I'm near spot on. So after flushing for tonight, and leaving plain water in for this light cycle, I'll then return normal (slightly lower perhaps) feed as well as the h202, or do I just run the peroxide on its own at first?

I'll research whether sterile is my best option or the beneficials for next grow. Planning DNAs 24K gold. If you know of any particularly good sources I'm keen to learn so would be gratefully received.

My tap water is chlorinated. But I think its a very low level and possibly off gases before it can make a difference. At the risk of answering my own question. Would this discount me using the beneficial bacteria? Or would i just need to run an airstone through it a while before adding?

Bleach is by far the best and cheapest.Theirs calculator on line just google..You type in the percentage and it will give you the dosage for 3-5 ppm.
Ive done 29% h202 at 1ml/gallon.Delute down first then add,i did twice a week.

Root rot will look like your plants got fed gasoline all sorts of deficiency's.I dont think your there yet but could be starting,as said ph drops.