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UnderMirkwood

RDWC Newbie

17 posts in this topic

Hi guys and gals, I am just about to try a RDWC system for the first time after growing in compost for many years. I have bought a ready made system which comprises of 4x21 litre pots and a 21 litre reservoir, my main concern is how much water do I put into the system to start with? Do I fill each pot individually, or do I fill the reservoir and let the system fill itself? 

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Posted (edited)

if its rdwc then it will all fill to the same level as they are all connected but stick to filling and emptying from the res do you have a water chiller ?? if you dont get some lcd thermometers put in the pots so you can monitor temps depending on size and type of light it will help stop root rot from warm water :) 

fill it quite high to begin with but not so its touching the bottom of the net pot then when roots start going in water lower it a bit so the roots keep growing down untill you have got to where you want them 

Edited by doobie01
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i fill mine at the start so it is just touching the underside of the pots.

When I put a clone in, or rooted seedling/ cube, I always put a layer of hydroton in the bottom of the net pot, then place the roots on top of this layer, holding  the stem a little higher if possible, then slowly back fill the net pot.

Good luck with it, hope they fly.

keep an eye on res temps and check the roots don't grow into the pipework.

a handy tip is to rotate your pots daily a 1/4 turn

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Thanks both, I don't have a chiller connected but I am aware of possible issues arising with water temperature so I will be keeping an eye on it. I will be adding Pythoff as a preventative measure and I figured that if I make regular water changes I should be ok until I can afford a chiller.

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As long as you're controlling your room temps, you can do without a chiller. Just keep them in the low 20's and the res should stay within the healthy 16-20 degree range. Air cooling my lights made a massive difference and when I had my smaller tent I cut two small holes in the side for my tubing and ran the control bucket from the outside. That allowed me to monitor and adjust the water during lights off, as well as aiding in keeping the res a little cooler than the tent. Then again I was using a 5 bucket 33L system which meant that temps fluctuated less and the thermal mass of the larger reservoir meant less temperature movement between lights on/off, so the battle wasn't too hard for me. Obviously a chiller is ideal but you can get away with it if you've got proper control of your growing environment temperatures and keep the air temps from getting in the high 20's.

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welcome to the fold brother 

 

:innocent:

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also.....Do I mix up the entire nutrient solution (100+ litres) before adding it to the system or do I add the water then make up the nutrient solution and then add it to the reservoir?

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Posted (edited)

i usually fill  the system with water, then add the nutrients to the res, then pump them round the system for a good 20 minutes before checking ph and ec.

Put the silicone in first, to prevent the water going cloudy. start with 0.25 ml per litre

then add the grow, if it is a part A and a part B, wait 20 minutes between adding part A and adding part B

Then ph down at the end, but make sure you just  add a little at a time and let it circulate the system. I dilute my ph down with water to make it weaker, so there is less chance of me adding too much.

ALLLWAYS check it an hour or so after all this has been done to make sure it is still the same EC and PH.

 

It sounds a bit complicated, but its not really, and once you have done it a few times you will get a feeling for how much of each to add

Edited by badbillybob
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Cheers badbillybob that's exactly the advice I was looking for...wicked :hippy:

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badbillybobs advice is spot on, I'd just like to add that a water butt helps massively as not only can you mix your next res way in advance to make sure it settles in the right range, a few days sitting in the tent (or outside, I just have the space inside) gives the water a chance to warm up to a similar temperature to the existing res. You'll find that the cold tap gives water under about 14 degrees, which is really too cold for the roots and can cause a little bit of shock. I know some people add boiling water to bring it up but that's just a massive PITA with my size reservoir and I'd rather not risk mixing with the hot tap as I can't guarantee it's sterile.

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3 minutes ago, SevernValleySavant said:

badbillybobs advice is spot on, I'd just like to add that a water butt helps massively as not only can you mix your next res way in advance to make sure it settles in the right range, a few days sitting in the tent (or outside, I just have the space inside) gives the water a chance to warm up to a similar temperature to the existing res. You'll find that the cold tap gives water under about 14 degrees, which is really too cold for the roots and can cause a little bit of shock. I know some people add boiling water to bring it up but that's just a massive PITA with my size reservoir and I'd rather not risk mixing with the hot tap as I can't guarantee it's sterile.

 

 

I have to agree here as well....Badbillybobs advice is spot on (especially the silicon bit).....but (as svernvalleysavant says) if I had(when I had) the room I would premix solution before putting in the system....get it at the right temp, E.C and PH before putting in.....let it settle.....check and recheck before it hit the system.....I know its perfect then as it goes in.

 

I have to use the 'Badbillybob' method now as I have not got the space for an extra res.....over time you get the feel for the water and know what concentrations of nutes you need to maintain the system

(for example...I now know 10ml of A+B equates to 0.1 increase in E.C in my system....I know roughly how much PH down is required to move the PH 0.3 points etc)

 

The best advice badbillybob is giving you IMO is the add SLOWLY part......big jumps in RDWC do the plants no favours and I have been relearning my craft with his and others help.

 

:yep:

 

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Posted (edited)

2 hours ago, UnderMirkwood said:

also.....Do I mix up the entire nutrient solution (100+ litres) before adding it to the system or do I add the water then make up the nutrient solution and then add it to the reservoir?

 

Dont think I read this bit quite right???????

 

The top up res should be neat water IMO (little bleach if its getting hot).......you can make it at half strength of the system but in my experience this will cause problems.

 

I like to stay on the side of just underfeeding (neat top up)...rather than risk the just overfeeding (nutes in the top up)

 

Depends on your skill level....ive been doing hobby/small scale for nearly 20 years and I still dont feel comfortable with nutes in the top up.(mans still an enthusiast....not a master)

(I may change this for blue cheese as I know the strain better than the back of me hand - its all I did for about 15 cycles)

Edited by zen-ken
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What I meant was, do I mix up enough nutrient solution to fill the entire system? When I say reservoir I mean the bucket that feeds the rest of the buckets, not a seperate water butt.

 

So do I just top this bucket up with nutrient solution while monitoring the EC and PH levels? Or do I change the entire solution/all the water every time the EC/PH changes?

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Posted (edited)

Yes....follow the advice badbillybob gave you :yep:

 

You completely change the entire water every week...you can leave it for 2 or 3  but everybody will recommend once a week (in bloom)....its gets brackish IMO if used for too long.

 

Changes during the week are adjusted through the 'header pot' and checked an hour later to assess and manage the change.....will take an hour to make sure the water has mixed properly.

 

If EC rises or PH keeps dropping a lot....... something is wrong and sort it.....quickly! (usually over feeding does this)

 

Get a grow diary up and bask in the glow of the knowledge of these guys...you won't regret it :yep:

 

I have nearly 20 years under my belt and Im still asking the masters for help :oldtoker::oldtoker:

Edited by zen-ken
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Posted (edited)

Say I needed 1ml/litre of A + B in my mix......it takes me about an hour to get it in......a little in the header....a little more...then the rest. (usually start this when system is about 3/4 full and I turn the return pump on so it starts to mix.

 

then Cal mag.....half at first.....half an hour later the rest.....if you put it all in at once the e.c in the header is so high it will burn the first plants on the system.

 

After an hour I will return and adjust if necessary :yep:

 

(put the silicon in first if you use it as badbillybob is advising....it clouds the water something fierce if you dont)

 

Edited by zen-ken

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