Flushing

[Gaytimegrower]

This is probably a stupid question but here goes anyway. If I dont ask, me like a lot of others probably wont know the answer.

 

I am growing hydroponically indoors using expanded clay and a recirculating system. I change the water every 2 weeks and have been told to flush the pots with pH adjusted water until the output CF reading is the same as the input reading.

 

When you have to flush 15 pots several times with ph adj water, that is one hell of a lot of water, not to mention the time, chemicals etc. involved in getting the water right to begin with.

 

What's wrong with using ordinary tap water as after flushing, the clay in the pots is going to be fed with the correct CF of nutes and ph balanced water anyway. There is nothing to stop us from pouring a litre or so of the corrected fluid evenly over each pot and if need be, correcting the ph afterwards. I am talking about pots that drain almost completely, not hold 1 or 2 inches of water in them. Even so, the pots could be tilted to drain any excess.

 

Surely there is an easy answer to all this. It would be easy enough to have the return line connected to a hose which runs outside and then just flush with another hose connected to the mains, or isn't this scientific enough?

 

Your input would be most welcome.

[Tom]

What is the PH of your tap water and how much chlorine is in it? You should still let tap water stand overnight before using it but if you are pressed for time fill your buckets with the hose using as fine a spray as possible, you will actually be able to smell the escaping chlorine.

 

Don't worry about a few dregs of water left in the system, the plants won't care.

[Luke Skywalker]

Ph adjustment allows the salts encrusted on the surface of the media to be easily returned to solution. Less water is needed to remove the salts accumulated if it's ph adjusted. And the expanded clay will be set at a high ph if you don't adjust it to the levels required, as they are "set" to some degree by the water they are fed.

 

The chlorine question is debateable imo, but a good idea to use water you've allowed to stand if you can. No harm I've seen yet that I couldn't attribute to my own stupidity rather than chlorine. Anyway, hope that helps mate.

[Gaytimegrower]

Hi mate and thanks for that.

 

I flushed all 15 pots till the water came out the same as it went in. cf2.8,

after that, I flushed with the hydro mix. Why should ph balanced water dissolve salts any easier than plain water? I really dont get the reasoning for all these things.

From what you say, if the tap water is going to alter ph etc in the clay, why wont it be countered when I flush with the nute solution. Surely, it is the same thing. Balanced or un balanced. As you have said to me in the past, it is only a weed.

I am sorry but I just cannot see the need to flush multiple litres of ph balanced water down the drain when a hose can do the same job and a hell of a lot easier.

I used the garden hose, slow run and flushed each pot. I checked the output cf and when it was the same as the tap water, I went to the next pot. I have a seperate hose connected to my return line so I can measure what is returning before it gets to the tank.

[Luke Skywalker]

Check the ph of your runoff GTG. The ph of the nutrient solution should be around the 6.0 mark inside the pots. Test it directly after flushing with that ph 9 water, and then after you've run a single flow of adjusted nutrients.... You'll see it's substantially altered by flushing with unadjusted water.

 

The reason ph adjusted water absorbs and flushes more salts from the water is that the ph levels of the water can alter the ionic form of the salts in solution. Making them less absorbable and even precipitating them out at high or low ph levels. Check out the faq and you should see some charts showing relative absorbtion levels in varying ph. Where does the unabsorbed salts go? You guessed it, it precipitates out onto the surface of the media and as a precipitate in the water. And in this form the plants can't touch it.

 

By all means, flush with hose water, but the water where I live is around ph 9 or so, so it's a fair effort to get just about any salts to dissolve completely and fully into that without ph adjustment.... You'll in all likelyhood end up having some nutrient issues if you're regularly flushing with ph 9 water, but hey, it's your crop.

 

Hope that helps mate. You may find it easier to simply set up a second reservoir and use that with a pump to irrigate all the pots in a Run to waste fashion. Periodic testing of the water should allow you to work out when it's done. That way you'd only need to fill up one container per week for flushing with a hose, and then after adjustment simply connect it up to the irrigation system and have the pots drain out elsewhere.

 

It's not too easy maintaining large amounts of pots, less is easier management, and IMO larger yeilds and turnover could be had. Bigger, and fewer, is better in my most humble opinion.

[Tom]

Chlorine is there to kill bacteria in the water supplies, it is indiscriminate so when added to the reservoir it also kills the good bacteria (including any you have added) that assist in plant growth.

 

Having said that my own philosophy is very similar to Luke's.

[Gaytimegrower]

Luke,

I dont know where you got that my tap water was 9. It is actually 7.

[Gaytimegrower]

Thanks Taz,

You mention chlorine killing off the good as well as the bad bacteria. I will have a problem then as I am using a product called Phytoff, made by Flairform, "leaders in hydroponics" as they say. It is supposed to keep the roots healthy and disinfect the system. "The All Purpose Hydroponic Sterilising Agent" It says on the label :

Active Constituent: Equivalent to 0.5% available chlorine.

So, does this mean it is bad for the plants instead of good. They are the manufacturers of "Dutch Treat" nutes.

I am getting totally and utterly confused with this whole thing.

www.flairform.com.au

[jackfrost]

The best way to flush your system is to do when you do your water change.

 

1) dump old nutrient out of res tank

2) fill res tank with fresh water

3) PH down fresh water to 6.2grow or 5.5flore

4) Pump ph adjusted through system for 15-20mins

5) Dump out flushed water

6) Fill res tank with fresh water

7)add nutrient and adjust ph.

 

You should only have to flush system if your CF has gone to high. A CF of 2.8 is a little high if you dont have CO2.

 

Try to run your CF at 2.4 max (with no CO2) and slowly bring it down to 1.4 over 7 days.

 

You can bring your CF down buy taking out a bucket of nutrient water and adding a bucket of fresh water.

 

Fortnightly waterchance is ok for the grow period, but when floring change water every 7 days.

 

JF, peace

[white_cluster]

just use that shit for sterilising/cleaning your system empty mate or if you get some root diesease, if your water is nasty then use something thats tried and tested like h202. its bad for plants too, but I wouldn't think as bad as chlorine.