2 rooms, same everything (almost) - one happier than the other

My primary room in an outbuilding. Had an aweful last crop for reasons that I put down to cold. Fairly sure of this. Only other change was switch from a GT424 tank to a GT100 tank. Rectangular 42 litres to square 100 litres.

Now heating it, and running a near identical room indoors.

Both rooms are same size, NFT, same lights, same food, same plants. Only difference is one is in an outbuilding, and that one has a GT100 NFT tank, as opposed to the GT424 indoors.

I'm noticing that the outbuilding grow is not quite as happy as the indoor one. The outbuilding one is 2 weeks behind in timings, and consequently still in veg whilst the indoor is now 10 days into 12/12.

The outbuilding plants don't look as vigorous, the tops weem to be a bit "wilty" and "stringy", and some leaves are showing clawing / inside curling (the disaster crop in the same room clawed badly during flower) already. Growth rate is fast. Indoor grow is super happy.

Below is indoor. Remember it's in early flower, but as you can see, super happy (and under sodium hence yellow - I switched the bulb over literally 10 mins ago, so thats not a factor)



Bel;ow are two shots of the outbuilding grow, under MH.





See what I mean?

Outbuilding room:
min 15 c at night, max 22 in light. PH floats around 6 ish. I drag it down to 5.5 occasionally, it climbs back to 6.5 fairly fast.
EC around 1.2
Heated with an oil filled rad on a stat.
Tanl res heated at constant 20 c with an aquarium heater

Indoor room@
min 16c at night, max 22 in light. Ph same, but strangely doesn't climb as fast.
EC around 1.2
No room heating needed.
Heat tank at constant 20

I'm now starting to suspect the tank change. The GT100 uses a HUGE pump with a spray bar. So huge (1000ltr/hour) I swapped it down to a 500lt/hour pump, and then put a valve inline to slow the high pressure jets to a more sensible flow rate. Other than that, I'm out of ideas?

No signs of any insect or organic problems.

Air?Out building off gasing from years of getting wet ,dry.
What was the out building used
for in its former life?

Does the outbuilding have good ventilation? Asking for CO2 levels.

Outbuilding is a garage. Nothing has changed in it. 4" input fan, 5" outlet, running on hybrid controller. Indoor same (though passive input). Very well ventilated building (and large). I have a very rarely used car in it (had bumper crops in summer when car used daily).

Outbuilding has produced stellar crops before.

How many of your indoor rooms will fit in your outbuilding?
If you move say 300 cubic ft air indoors then outbuilding needs that many more times.One 5" fan in garage is not nearly enough.

It's a big garage mate - a double garage. with a 4x4 tent in it. My indoor tent is the same , in a room barely 4 times the size of the tent.

The 5" fan blows outside, and is fed by a 4" fan (garage) . Worked wonderfully for 3 grows before.

These are RKV fans - blow your wig off on full!

Why does the garage tent need to move more air than the indoor one? Perhaps I didn't explain - both "rooms" are in sealed 4x4 tents

Only reason I bring it up is home CO2 levels are often high because of the fact humans and pets are exhaling and even using gas stoves adds a lot of CO2. Just wondered since you say everything is the same if there was a problem with CO2 levels not being adequate.

Hmm. Interesting. Maybe using my petrol car frequently adds Co2 to the garage in summer. Still, I'm drawign in what is effectively outside air, and plants manage outside...

Is the pH fluctuating differently on the two systems?

NM I just read that in your post. Thats likely your problem, the fluctuation is giving them what they want. They don't like being so high all the time. Try lowering the pH in the outbuilding.

oh yes ok I see,as Renfro says still different air quality.
Maybe fart more often in the garage.

Yeah - the garage grow, for some reason, has less stable PH, which is a suprise as the reservoir is twice the size. I expected more stable PH.

I put 4ml of PH down in the other day when it climbed to 6.8. That would normally bring it down to around 5.5 to 6 (I do it in controllable steps) but it brought it down to 4! I was amazed. I flushed the tank and refilled.

Perhaps larger tanks are less PH stable? I've no idea.

PH at 5.3 now, after two small adjustments this evening (2lm, then 1.5ml). Target = 5.5 with rockwool

Ok so 42l tank is small,is it hard to keep ph stable?100 litre is what I use in flower seems easier to keep ph as my veg one is 45l.
ha opposite of what i find lol

myke said:

oh yes ok I see,as Renfro says still different air quality.
Maybe fart more often in the garage.

Click to expand...

Maybe lock my cats in there?

myke said:

Ok so 42l tank is small,is it hard to keep ph stable?100 litre is what I use in flower seems easier to keep ph as my veg one is 45l.

Click to expand...

Opposite. my 42 (it's 45 actually) is more PH stable. I've always grown in GT424 tanks (45 litre). The garage now uses a GT100 - 100l tank - that is the less PH stable one!

do u have air stones in your rez?

No Myke. Never found a reason for them with NFT, and they skew the PH, I'm told. I have one, but don't use it.

I ran it when my last crop in the garage had problems and it made no difference.

hmmmm well shit thought I had it.

Well look at it this way,you wont have to harvest both rooms at the same time

The garage is behind only on timing, not because of poor performance. The indoor room was fired up at least 2 weeks before the garage one.