Flushing ....

[Frazz]

 

hey Taipan would you please elaborate on some of the " many aspects that indoor growers are just guessing about"

cause i do alot of guessing

[Luke Skywalker]

I'd make a long, involved and detailed post as to why taipan seems to know what he's talking about, but appears to be proposing that we're all idiots....

 

Screw it I will.

 

Anyone who's ever grown a crop of MJ or anything else for that matter in hydroponics would be aware of the need for flushing if salt builds up to unacceptable levels. This can be in the form of a weekly fresh water flush, or a regular watering which contains far more than is actually required by the plant. i.e. more than 50% runoff to ensure that salt levels aren't able to build up to appreciable levels.

 

I'm familiar with the theory of flushing being detrimental, that the sudden change in osmotic pressure is harmful to the roots, but PRACTICE would seem to discount it. A lot also depends on water quality. Commercial hydroponic vegetable farms often have high quality water with precise control over content of nutrient ions, pH, temp, you name it. They usually don't use tap water either, which often contains literally craploads of dissolved sodium and chlorides. (not to mention the numerous other salts and metals present in some tap waters) This allows such greenhouse growers far better control of problems with individual chemicals added to solution to correct imbalances. But even they flush out crops when things get out of hand, and eventually in any system the salt levels in the media will build up unless sufficient solution is able to draw it out of the finest micropores of said media.

 

Water culture methods are a little different, but even then the small amount of media required for the initialisation of the plant and support for the base of the stem is quite prone to excessive salt build up due to evaporation and transpiration of the solution to the surface of the media. These systems also benefit from flushing, although it may not be necessary every week, perhaps even not two, but eventually you'll find the salt levels in water passed by that media will be significantly raised in e.c.

 

Sukonmi has pointed out the differences between crops grown under greenhouse conditions such as herbs, lettuce, tomatoes etc, and you should keep in mind that the finished product is smoked, not eaten. Dissolved solids and salts in fruit and vegies are wanted as they improve flavour in the product. In cannabis this isn't desired, as the finished product is often inhaled after vaporisation or burning. Salts present in these kinds of products seriously harms the flavour and some say even the health effects.

 

Properly grown, cured and dried MJ is a very different proposition from vegies.

 

nuff said.

[bufo marinus]

I'd make a long, involved and detailed post as to why taipan seems to know what he's talking about, but appears to be proposing that we're all idiots....

 

Thats a little harsh, I thought taipan was reasonably diplomatic?

I thought everyone raised some good points actually.

What he said regarding the use of lower nutes as a way of minimising flushing with a quick crop such as mj made sense to me. I didn't think he was arguing against a final flush, so..... ?

Good thread I reckon

[Taipan]

Whoa taipan you sure know how to kick up some dust , hehe. I've been coming around to the use of lower nutes too and have started using a light flush as a way of being able to measure and bring the EC back down to 1.0 (and the pH back up to 5.5)in the coco,... just thinking about it the plants have looked really good the morning/day after

I still sit the res at to 1.6-1.7 and wonder why it only takes a week to build up to 2.0 in the medium hmmm

I've also been using Superthrive when I flush as I thought it would be useful then

Yeh, I guess people are very passionate about flushing.

 

In your situation, you say it takes a week for the EC in the medium to build up to 2.0. To me that says you need to lower the EC in the res. If you consider your ideal EC to be 1.6-1.7 you should maintain an EC in the res that gives you the ideal EC in the growing medium. If it starts to build in the medium, lower the EC in the res even more. In hot weather you can end up with a very low EC in the res and still maintain the correct EC in the medium. In cooler weather the differences between the res and the medium will usually not be as much.

[Taipan]

mmm pot forum mate... unless you specified about hydro veges.. then we would all just assume.. as EVERY one here has.. that your talking about MJ...

If you read the original post I made this point "Do not think that a hydroponic system for indoors is any different to a hydroponic system for outdoors, hydroponics is hydroponics and the people to learn from are the growers who grow multi million dollar crops for a living." Pretty obvious what I was talking about.

 

at the hydroponic herb farm i used to work at we would flush every three days... thats had nothing to do with the crop.. and had EVERYthing to do with cleaning and maintaining the systems... as for flushing the plant like we do for Mj to rid it of all that hydro/fert taste .. well that doesn't happen...

That's one farm, I know loads of hydroponic farmers and visited many others worldwide and none of them ever flushed a crop with pure fresh water while they were growing them. Final flush in MJ is a whole other story, I am not even talking about that.

 

are you in Australia?.. we have VERY strict guidelines as to how food is either grown or killed.. huge scale operations that grow .. lets just say herbs..as this is where I have my experience ..have guidelines on the cleanliness of the systems.. nutrients.. and pesticide sprays... the herb systems were all in a NFT style so the pumps ran 24/7...every time a table was harvested it would be pressure cleaned to blast out all the algae ...and clean the treys for the next planting.. now most herbs would be ready in about 6 weeks.. parsly was about every 4.. very fast in the hot houses... so each table wouldnt even go 8 weeks with out a thorough clean... the tanks were flushed and dumped and refilled with fresh water and nutrients every 3 days.. with out fail.

 

now as for running clean water through the actual system to flush the system like we do for mj.. that never happens as the plants would probably suffer.. this doesn't happen with mj.. for reasons ive previously stated..

Yes I am in Australia. I don't see what cleaning systems between crops or pesticides has to do with what I was talking about. And the tanks being flushed and dumped and refilled with fresh water and nutrients every 3 days, is not the "flushing" that I have been talking about either. I am talking about pouring fresh water through your growing medium. It will be less stressful to your plants to do it with a weak solution.

 

To address the part about waste and toxin removal, this occurs during a normal irrigation cycle. If you have a run to waste system you need at least 10% runoff, with a recycling system the regular irrigation cycles will remove the toxins from the root zone.

Edited February 1, 2007 by Taipan

[Taipan]

I'd make a long, involved and detailed post as to why taipan seems to know what he's talking about, but appears to be proposing that we're all idiots....

 

Screw it I will.

 

That's just twisting my motives way out of proportion. I have seen many posts where people have recommended doing a major flush as a method to fix a nutrient problem, I did not once post to contradict that advice. I am not saying anyone is an idiot.

 

Just because a plant can be flushed regarly with fresh water and still grow a good crop, doesn't mean it's the best thing to do. It's a weed, it has very broad tolerances for nutritional requirements. Try growing a whole crop on tapwater .... not nutrients at all (EC around 0.3), from start to finish. I've done it and you'd be amazed at what these plants can do. You'd expect a yellow plant which would not grow much at all, well when I did it the plants grew quite healthy and gave a yield of around 30-40% of my usual plants.

 

The reason for my post is not to tell everyone "stop doing what you are doing" but to just spark a bit of thought towards maintaining the "growing medium" not the "res".

[Luke Skywalker]

My tapwater e.c. is nearing 0.9, so don't tell me to grow with crap water cos I've been doing it for years. It makes life incredibly difficult. When you've had to cope with a ppm level that's past WHO recommendations then you can claim to have grown with shite water. 0.3 e.c. is minimal.

 

I've gone to the expense of an RO filter for my plants now, and even so I KNOW I need to flush as e.c. levels begin to rise in the recirc system after about a week and a half. Water collected from run off is significantly higher than the e.c. when it goes in after 2 weeks with no flushing.

 

Maintaining the growing media is exactly what we're talking about. Take a reading from water which runs through a pot which hasn't been flushed and you'll pretty quickly see the levels rise if you don't flush at least sporadically.

 

It's far better to flush and not need it than not to flush but need it. Any possible harm (which I'm yet to really see anyone document in anything other than "this should happen if you do that" statements) which may come to the plant from a drop in e.c. levels is vastly outweighed by the benefits of keeping a clean and stable media.

[Taipan]

My tapwater e.c. is nearing 0.9, so don't tell me to grow with crap water cos I've been doing it for years. It makes life incredibly difficult. When you've had to cope with a ppm level that's past WHO recommendations then you can claim to have grown with shite water. 0.3 e.c. is minimal.

 

Take a reading from water which runs through a pot which hasn't been flushed and you'll pretty quickly see the levels rise if you don't flush at least sporadically.

 

Actually I am talking about growing a whole crop on tapwater, adding no nutrients at all, as an experiment. I didn't say anything about crap water.

 

If the EC of your runoff rises quickly then you are feeding them too strong. If you feed them the correct strength then it won't rise much at all, hence removing the need to flush.

 

The way I grow involves the least amount of effort with the best results I have ever had or seen after 30 years of growing, just thought I'd pass on a few tips. Pretty obvious that you think I know shite all about what I am talking about so I am going to shut up now.

Edited February 2, 2007 by Taipan

[F420]

Nah dont shut up mate, this is a forum for discussions. weather or not people do it that way is up to them.

 

Luke uses R/O water, I personally think its crap and would never use it, as once again your not giving the plants any macro elements. R/O water was never designed for growing plants. But then if his water is shit, then he needs to do something with it.

 

If your not sure what im talking about with problems using R/O water, just ask Chato about his experiances with it.

 

People do things the way they know works, and if its working then dont change it.

Just because we have seen that certain things do or dont work well for us, doesnt mean it wont work for the next person. Climates change, tap waters change, theres alot of variables involved.

 

i have just brought a Power grower from General Hydro, and the instructions say to either use TAP water or to buy thier product thats suited to hard water.

[SukonmiSkunk]

ok.. using tap water is not the best shit to use for indoor set ups... its a compromise and I bet if you ask any grower.. that grows... that if they had the choice they would opt for a RO filter..

 

water varies in every part of Australia.. down here on the Limestone coast where I live.. you wouldn't even use the tap water for drinking.. once you boil it and see the lime and calcium build up in the pot.. quite unlike ive ever seen before.. you would understand why every house has a rainwater tank..

 

I use rain water.. plants grown in rainwater .. or RO water are a shit load better than plants grown on tap water... especially where I am... my rain water measures at around 40-50ppm.. id like to see anyone grow anything on that.. considering even with such pure rainwater... I still get nutrient deficiencies in the form of rust spots, patchy dark green.. and an all round yellowing of the leaves ..when my ppms drop to below 1200.. this tells me that the ppm levels is no where near high enough... hence why I run my tank at 16-1800ppm... trust me.. I am not a big fan of pumping plants with all sorts of crap to boost size or yield.. and if I could run my ppms lower I would be... as it would most definitely make the grow a lot more cost efficient.. and lets face it.. indoor growing is really down to cost and efficiency.. right? im all about saving money where I can.. as are we all...

 

the cold hard facts are... the plant needs certain levels of nutrients to grow and produce resiny flowers.. with just a slight drop in these levels will almost definitely reduce yields and flower size... hence the reason for enhancers.. Im pretty sure if they didnt work.. people wouldnt be using them???

 

my advice to any indoor recirc hydro grower.. try using rainwater for your next crop..unless of course you are already using an RO filter... you will taste the difference dramatically in the end product.. and I put the quality of my grows as purely down to the use of rainwater... as my flushing and final flushing techniques havent changed from when I was in the city and using tap water... which I used for years.. with great results... but nothing like im getting now with a cleaner water source...

 

adelaide tap water at the time measured at around 600-750ppm.. on any given day... so I can see where ya coming from about using just water for your grow.. how ever.. id lacks the potassium and phosphorus levels you need for flowering... and the nitrogen levels needed for growing...but even then I was mixing the ppm's to around the 1800 mark...

 

show us some pics of a plant grown in straight tap water.. and ill show you a plant with every major and minor deficiency known to MJ growers

 

I remember some one telling me the same thing about 1996.. saying you can grow on tap water.. so I tried it.. I will NEVER be that fucking stupid ever again... as it was about 3 weeks into the grow.. that I decided he was a fool.. and added nutrients to my grow... never again...

 

so all in all .. this is a good thread... and people can use information from both sides of this .. argument.. and do some experiments and find out them selves.. as I have done.. many years ago...

 

growing for personal use is down to personal choices.. and I encourage every one to play around and find what works for them.. as what may work for me.. might not work for you... there are so many products out there that work very well .. so its really just down to perfecting your nutrient program to suit yourself... and your plants...

 

yes MJ is a weed.. and yes MJ will grow in nearly any condition.. its a very resilient plant.. and can really adapt to most situations... how ever indoors under intense grow light you are a lot better of to give them what they need.. your yields and quality will certainly be a lot better...