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Do YOU flush DTW rockwool/coco?

Mudraya

Mudraya

Active member
Conventional wisdom states that if ppms are high in runoff you can flush, add a feed, increase runoff % or reduce EC/PPM. I'm running rockwool but DTW rules can be very similar with coco so included that in the title.

Just curious what the consensus is here. Do you feed higher ppm and flush weekly/biweekly to bring down the runoff to acceptable levels or feed low until you get virtually the same going in and out and no flush 'till flush time? This question is for those who are testing their runoff. Alternatively, are you feeding high with a high runoff like over 15% ? MORE IMPORTANTLY, are you someone who used to feed high and now feed low to target similar runoff and are now getting better results?

Thanks!

P.S. Mods: maybe this belongs in the nutrients forum? Idk you decide. Seemed like more of a hydro issue though...
 
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Bush Dr

Bush Dr

Painting the picture of Dorian Gray
Veteran
I'm in coco and would never give a plain water flush, reduced feed has always solved it for me during the flower cycle ....flush plain water at the end for sure

Dansbuds is the guy you should ask, PM him
 
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M

mushroombrew

Active member
Veteran
Yeah I'm here...

I run Perlite/Rw croutons. It drains fast.

I just water as normal with about 10% runoff. Once a month I like to give them fresh water to flush salts. But in DTW salts get flushed out all the time.

If I don't flush it takes about 12 wks and then I get salt stress/burn.

My runoff numbers are very close to feed numbers. If they go up drastically then back off nute concentration. The other thing I suggest to help you get there is make 3 different solutions. Say 800,1000 and 1200 ppm's. Easy to do in a few buckets etc.

Then check growth and see what's best.

Edit:- 3 solutions for 3 different clones/plants
 
D

DelTaco

Member
I’m growing is 6x6 rockwool for the first time and I have 1 week before chop. I water 600 ppm to achieve 10-20% every day and never flushed. No tip burn for me.
 
Mate Dave

Mate Dave

Propagator
ICMag Donor
Veteran
It depends on your setup mainly, the whole garden design as well as genetics for what & how you to plan to cultivate said crop. If your handfeeding plants in 20+ litres of coir or a wole bag @ a time then your not gonna lift or tilt that pot to test the last vestiges of runoff or furthermore get enough flow through the rhizome handfeeding to keep the medium from 'swinging'.

This mostly depends on the dose from the initial charge of the coir to the daily feed regime.

Coir is more noob friendly for cultiuvation of commercial weed than I would say plain Hydro is but the tank allows you to 'Dial' in the feed on either method with more control. Less manual labour...

Coir takes longer to release it's PPM's with standard top feed from my experience but it has a microbial relationship with the plants.

You also can't be expecting the commercial guy with 40 plants under 10 lamps to be doing runoff tests? Each plant will take 4 litres of water a day in a 20 litre bucket & more if grown well. Your using the drip tray here to good effect to prevent swing in more ways than one. To stop the salts & media drying out causing burn & also because they will suck up the liquid feed in there anyway, depending on the E.C. The feed in this scenario you can use the drip trays to speed up the watering & monitor transpiration allowing you to visit one time per day..

It comes down to how much water/time have you got to flush clean the system, is it @ a premium i.e. does it need to be filtered or on a meter & more importantly can the genetics take beast mode.

There is no better way, just good dope & bad cultivation
 
G.O. Joe

G.O. Joe

Well-known member
Veteran
550-650 ppm 5.5-5.8 pH from as soon as the plants can take it to chop works best for me. If the plants don't like it I blame the strain and move on. More runoff fixes high runoff ppm. Lots of runoff doesn't bother me.
 
Mudraya

Mudraya

Active member
Thanks everyone for your input. I ran a closed system for years with very high ppm like 2.2-2.4 EC and it worked really well for awhile. I think it was because it was coco and there was a bit of a buffer. Now I prefer rockwool and got tired of dealing with crazy fluctuations in the res and decided on a new approach.

I've done a ton of reading on here and elsewhere and still trying to wrap my head around running an EC as low as .3 and even 1.2 which seems to be the average. It makes sense logically but experience has me baffled. It's amazing how much less nutes and water can be used and still get a good result. Just started doing 8x/day with 7% runoff at 1.2 ml/sec for 76 seconds. Grodan101 recommends a 3% irrigation which is 102ml in a hugo and I'm close to that target at 91ml. Was running 2 EC initially during stretch and system runoff is 4 EC (!!!!) but is 2.8 when taking a liquid sample from inside the hugo. I've started gradually diluting the res every day by .25-.5 until the block sample is the same as the input. I've read that the reading from inside the media is the best test.

Can anyone explain the discrepancy between the reading from inside the media and runoff in rockwool? I'm wondering if it is salt deposits in the tray or drain.
 
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Phaeton

Phaeton

Speed of Dark
Veteran
This is not instruction, it is merely the way I do the watering.

Rockwool croutons with 1.5" of Perlite topping (bug barrier).

Water (nutrient) equal to half the container volume. Most are 18" diameter by 9" deep holding 7 gallons.
3.5 gallons of nutrient twice per day. Runoff is between 2 and 2.5 gallons.
The smaller 12" by 12" containers hold 3.5 gallons and get 2 gallons added with a bit over a gallon runoff.

Self flushing was my opinion for over 8 years of growing. Then a friend said the batch I test flushed came out better, a lot more tasty and smooth. I vape an extract and could not tell the difference but others chimed in with the preferred taste of the flushed bud.
The last few years the plants have been flushed for the last ten days to good effect.
 
M

mushroombrew

Active member
Veteran
Phaeton said:
This is not instruction, it is merely the way I do the watering.

Rockwool croutons with 1.5" of Perlite topping (bug barrier).

Water (nutrient) equal to half the container volume. Most are 18" diameter by 9" deep holding 7 gallons.
3.5 gallons of nutrient twice per day. Runoff is between 2 and 2.5 gallons.
The smaller 12" by 12" containers hold 3.5 gallons and get 2 gallons added with a bit over a gallon runoff.

Self flushing was my opinion for over 8 years of growing. Then a friend said the batch I test flushed came out better, a lot more tasty and smooth. I vape an extract and could not tell the difference but others chimed in with the preferred taste of the flushed bud.
The last few years the plants have been flushed for the last ten days to good effect.
Click to expand...

Damn that's a lot of nutrient. 7G per day... You save it right? Recirc?

Have you tried GS2? Cheaper than perlite and bugs hate it. I use 2" on top.
 
M

mushroombrew

Active member
Veteran
Mudraya said:
Thanks everyone for your input. I ran a closed system for years with very high ppm like 2.2-2.4 EC and it worked really well for awhile. I think it was because it was coco and there was a bit of a buffer. Now I prefer rockwool and got tired of dealing with crazy fluctuations in the res and decided on a new approach.

I've done a ton of reading on here and elsewhere and still trying to wrap my head around running an EC as low as .3 and even 1.2 which seems to be the average. It makes sense logically but experience has me baffled. It's amazing how much less nutes and water can be used and still get a good result. Just started doing 8x/day with 7% runoff at 1.2 ml/sec for 76 seconds. Grodan101 recommends a 3% irrigation which is 102ml in a hugo and I'm close to that target at 91ml. Was running 2 EC initially during stretch and system runoff is 4 EC (!!!!) but is 2.8 when taking a liquid sample from inside the hugo. I've started gradually diluting the res every day by .25-.5 until the block sample is the same as the input. I've read that the reading from inside the media is the best test.

Can anyone explain the discrepancy between the reading from inside the media and runoff in rockwool? I'm wondering if it is salt deposits in the tray or drain.
Click to expand...

Oh you cannot measure runoff EC in the tray. Collect the runoff straight out of the pot. The tray is super salty.

I saw 4.0 and I was tripping. Plants cannot live in that test must be inaccurate. So you are contaminating your sample with tray salts I think.

Pour nute into pot. Catch in 5G bucket. Measure again.

You Follow?
 
Mudraya

Mudraya

Active member
mushroombrew said:
Oh you cannot measure runoff EC in the tray. Collect the runoff straight out of the pot. The tray is super salty.

I saw 4.0 and I was tripping. Plants cannot live in that test must be inaccurate. So you are contaminating your sample with tray salts I think.

Pour nute into pot. Catch in 5G bucket. Measure again.

You Follow?
Click to expand...

Yeah, has to be a salty tray/drain lines. I can't lift the plants as they are under a net now. They are not in pots but in 6" hugo blocks. Next time I'm using growcubes in a floraflex potpro that has legs that give a little bit of clearance underneath so that sort of thing will be easier at that time.

What I do is put a syringe in the lower 1/3 of the block and extract just enough liquid to take a reading with my meter. The article linked above also claims this is the best way to test.

I was just making an observation on the very wide discrepancy in the readings, pretty crazy. I almost lost my sh$&&t when my meter started blinking 3999....3999...3999 lol.
 
G.O. Joe

G.O. Joe

Well-known member
Veteran
Grodan's Water pdf says to saturate at sunrise to achieve a considerable amount of drainage, unless you're not at daily watering yet flush every time then. It tells how much to water also giving specifics for the 6" blocks. A quart of runoff is enough for 4's on 6's as I do them but I'll still monitor pH sometimes. Using less leads to a buildup not easily flushed. Grodan gives good to great advice I think except their rockwool might need a little more initial conditioning than they say.
 
Mudraya

Mudraya

Active member
G.O. Joe said:
Grodan's Water pdf says to saturate at sunrise to achieve a considerable amount of drainage, unless you're not at daily watering yet flush every time then. It tells how much to water also giving specifics for the 6" blocks. A quart of runoff is enough for 4's on 6's as I do them but I'll still monitor pH sometimes. Using less leads to a buildup not easily flushed. Grodan gives good to great advice I think except their rockwool might need a little more initial conditioning than they say.
Click to expand...

Yeah there are different opinions on that I guess. Many say you don't need to flush with multiple daily feedings as long as you have 10% runoff, but I've found that I probably need to. That is why I started this thread...to get a consensus. But it appears there isn't one lol. I water 8x/day. Thought my calculations were correct in getting 7% runoff but I'm getting 20% the last few days, probably from the cooler weather. I'm definitely running drip clean next time and starting with lower EC.

I saw someone claim online that they spoke to a rep and Grodan no longer needs conditioning, that you can water and plant, they changed the binder a couple years ago and it doesn't raise the pH in the media. The packaging is still the same as a precaution but not necessary.
 
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