hey y'all
i would really appriciate some help and know ive come to the right place.
done a few soil grows in the past but ive just finished putting togehter a flood n drain hydro system, it seems to work pretty well (only started running today) but i hav loads of queries...

what is the minimum temp i can hav my reservior at (in the garage)?

how often should i flood (16 plants in 4 litre pots, doin 3 15 minute floods per day ATM)

is there something wrong with my seedlings (they're C99 from seed, see pic)?

im using canna A+B nutes half strenght, at what stage should i work towards full strength?

roughly how often should i change my (68l) reservoir?

cheers, si

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Not res temps it isnt

20 degree res temps are bang on.You dont really want to be going any lower

Owd

cheers, think i might buy an 100W auqarium heater, my think that works out at raising the temp 1degreeC ever 40 mins, if i consider heat loss i'll probli hav to run it most of the time?

yeah, i was thinking my budget wouldnt strech to a tthermostat but i just found a 300W one with stat for £11 posted

you might want to get something like black & white to shield the rockwool cubes from forming fungus ?

never thake them out of the water when they are still warm, switch off and leave it for about an hour till it has cooled down then take it out, the sudden heat change causes the glass to crack mate
T1

I have just bought an Aqualine remote thermostat model which is brilliant and it was only £20. It has a stainless steel heater that you completely submerge, i have stuck mine to the bottom of my res tank, a stainless steel temp sensor which is also submerged in the res and then a remote unit that you plug in and set the temp using the dial. Mine does run a degree or 2 warmer than the dial but it is great. You just need a little bit of tape to cover the led's that show you when it is heating on full power or just warming but it does also have a low level alarm which sounds when the water is to low for the heater.

A highly recommended bit of kit.

My glass one broke on the flood and drain cycle as it exposed to much of the glass when it was heating!

just bought a glass one-gutted, ill try and lie it flat to prevent i smashing.
thanks for all the heating tips.
never tohught much about the algai, just put some black&white over it?
havnt reecived the heater yet but tunded up the light cycle to 20-4 to try and keep things toasty.
they're growing at a pretty impressive rate but still seem to be suffering, or maybe im just paranoid?
if anyone can see frm the pics what could be wrong with the little girls please give me a shout.[attachmentid=115799] [attachmentid=115800]

The droopiness could be overwatering. Can you squeeze water out of the 3" cubes easily? If so then they are probably too wet.

The interveinal yellowing looks like a nute def to me m8. What is your CF/EC?

im flooding them for 15mins 3 times per day, does that sound too much?
havnt got round to buying an EC meter, using canna veg A+B at half strength

It may be too much for plants of that size. They are only small. Can you reduce the flood time but increase the frequency? I am not an NFT man, I am F&D so i don't know what the flood cycles should be for your setup or for plants that size. I am just going from the pics.

You got to get yourself a CF/EC pen/tester of some sorts mate especially in Hydro.

First off mate, how old are your plants mate ???....To me they look about a week old possibly two, and a little poorly. Possibly under-fed ???

According to the Canna feed schedule for week 1 you want to be using 1.8ml of A & B per litre, week 2 the same or if they are up to it 2.2ml. Personally I would stick to the 1.8ml for a couple of weeks.
Get yourself an EC pen, you won't regret it, also have a look at the Canna website.

Res temp as Owderweb said around about 20/21 is spot on.

You want to change your "res" every week or two. I normally try and do every week but sometimes I leave it for 2-3 weeks with no problems.

Edit to add - I have'nt done flood and drain but your flood frequency sounds o.k. Are you doing one flood when light come's on or just before, another half way through lights on and one at the end ??

Hope this helps.

yeah there into their second week but didnt give them any nutes the first.

havnt prepared very well for this gow, but im learning! EC meter is ordered along with a heater (so far im keeping atmospheric temp at about 18dgC and the res stays about 9dgC, not ideal but i guess it'll hav to do.

flooding once before lights come on, again at "lunchtime" and again in the "evening" if u get me.

thanks for all the advice, pretty sure i got the nutrient mix right but will change the reservoir after xmas

this is FnD not NFT isnt it? think overwatering might be a problem but my cheap timers only work on 15min segments so i might switch to two floods per 24hrs.

thanks again for all the advice, MUCH appriciated

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When you flood the system does the water just touch the bottom of the cubes or does it come half way up em or completely submerge them? It should just touch the bottom IME as rockwool soaks up the water like a sponge. Anymore and you'll be drenching them and they won't have time to dry out enough, and get the oxygen they need before the next flood. The top 1/3 of the cubes shouldn't be really wet, it should be more dry than wet, damp is ok.

thanks for the advide, still experimenting with all of this! set to flood twice a day now, i read that its best to have a few longer floods than many short floods?
i'll cut down my drainage pipe and see if it helps, otherwise things seem to be going well as the plants climatise to the hydro system/nutes etc.

they're 16 days old now, know ive messed things up with them abit and u can tell from the pics that my growroom has been put togewther in a weekend. got a picture of them tonight, what do u think?
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Yep they look fine to me mate, 16 days u say?

Why the big chunk of rockwool? I'd chuck that crap and just stick with the hydroton. It is an excellent stand-alone medium. It drains far better than fiberglass, providing much more O2 to the roots. It doesn't have a tendency to hold fertilizer salts which, over time, reach levels so high plants burn. Just curious?

porgy

ps I'm gonna guess the leaves are curling under, and they are much punier than they would be, due to the 9 degree C nutrient solution. I understand, though, you are at the mercy of the mailman on this one. As soon as you get the heater in the res, you'll be fine. They look very good for cold weather plants!!

yeah abit of leaf curl, got the heater, stuck it on at 18C, that ok?
do u mean just have the plant in with clay pebbles, no rockwool at all? im a total novice but never thought that would work remebering they have to be transplanted once flowering?