Jump to content
  • Sign Up

Do you need to flush perlite during the grow?


Recommended Posts

Having a bit of an issue with the EC in the nutrient solution for my recirculating through perlite setup.  Nutrients I've been using are Canna flora 2 part with H&G multizyme and Canna PK 13/14, was using H&G 2 part up till a week or so into flowering.

 

It's been going for a bit over 2 months, and I flushed the crap out of the perlite before first using it, had a small amount of PH climb initially, but that has stopped ages ago.  Have been tending to run an EC of around 2.0-2.2 generally, but have had a couple of accidentally higher solutions, up to 2.8 once, but the 2 plants seemed to be loving the high EC and didn't suffer any problems from the couple of higher solutions.

 

Now about half way through flowering, and just finished PK 13/14.  Wanted to run a couple more days of it but this problem developing has cut it short.  When I first made up a new solution with the PK I accidently made it too hot, about 2.7 from memory, but thought they've handled it before and I'll just give it a couple of days and top up the res with straight water to bring it back down.  Little bit of burn on the tips of the leaves, but nothing scary.  Topped up the res 4 days later, but as the water level had dropped a lot I added more nutes to the solution, but at a much lower rate, ended up at about 2.5, thought it was higher than it should be, but didn't worry.  Then yesterday I filled the res from about half empty with plain water, checked the level and it was over 2.8, was sure it was plain water but may have mixed it a couple of days ago and forgot, but was definitely sus after that.  Checked today and it had risen to 3.4, brown trousers time.

 

Hence the question, do you need to flush perlite?  I had assumed not, but the only other thing that could explain it would be the plants drinking but not eating for some reason.  PH levels have been stable at 5.8, and up till yesterday I have not seen any signs of deficiencies, so that seems unlikely.

 

Anyway, I have run 2 lots of plain water through on continual flush for an hour or so, ended up with the 2nd lot coming in at 0.1 over what it came out of the tap at (0.2 EC), the first lot climbed to 1.4 before I changed it.  Probably need to keep an eye on it for a couple of days to see if that's taken care of it.  In the meantime I'll run an EC of 1.2 to see how it goes, hopefully it will be alright as the plan is to run half strength shooting powder for a week or two, and I need the plants in perfect health before using shooting powder.

 

Really would appreciate any thoughts/input on this, as mid flower is a fairly critical stage.  I'll need to wait till lights on to check the plants for problems

Edited by Sir PsychoHashy
Link to comment
Share on other sites

Over time nutrients that aren't used can build up on all mediums.  In recirculating systems this isn't usually a big problem as the nutrients get mixed back up in the water when the pump turns back on but it still happens which is why you can get clogged tubing and all that jazz.   I used to like feeding once a week and topping up my res as needed.  Come the end of the week I would dump the res, give it a clean and put plain pH adjusted water in it so I could run it through my system to give it a flush.  I always had the EC rise and the pH would change a little bit too but after 15 minutes everything was cleared out so I would dump the res, refill it with a nutrient mixture and set everything back up as normal.  These days I'm hand watering with perlite and need to flush every 3-4 days as my pH rises insanely even though I flushed it considerably before use.  Don't know why its acting that way but its sure making me miss my old recirculating system lol

  • Upvote 1
Link to comment
Share on other sites

I'm also in perlite recirc system and to answer your question simply, Yes you do need to flush.

I do so each fortnight by emptying my heart, topping it up with pH adjusted water then running that for an hour, emptying again and repeating 3 times over an 8 hr period

I also block off my returns and flood the pots before emptying again

ALWAYS with pH adjusted water.

 

Works for me

 

Merl1n

Link to comment
Share on other sites

Now about half way through flowering, and just finished PK 13/14.  Wanted to run a couple more days of it but this problem developing has cut it short.  When I first made up a new solution with the PK I accidently made it too hot, about 2.7 from memory, but thought they've handled it before and I'll just give it a couple of days and top up the res with straight water to bring it back down.  Little bit of burn on the tips of the leaves, but nothing scary.  Topped up the res 4 days later, but as the water level had dropped a lot I added more nutes to the solution, but at a much lower rate, ended up at about 2.5, thought it was higher than it should be, but didn't worry.  Then yesterday I filled the res from about half empty with plain water, checked the level and it was over 2.8, was sure it was plain water but may have mixed it a couple of days ago and forgot, but was definitely sus after that.  Checked today and it had risen to 3.4, brown trousers time.

 

lol

 

Yeah, all the salts building up throughout your system, perhaps. I like it give everything a good scrub once in a while.
Link to comment
Share on other sites

Thanks guys.  Sounds like I might need to flush it out more.

 

Thankfully the PH is stable at least.  No idea about your PH prob Dr, but you're right about the recirc system having advantages, at least when it runs properly.

 

Probably should add that the pump is on a 15 minutes every 2 hrs cycle.  Fresh solution weekly with top ups inbetween.

 

Also, EC has risen again by 0.15 after the last 15 minute cycle.

 

And more specifically the 2 plants are nearly 6 weeks from start of 12/12, looking at between 9-11 week flower cycles.  I suppose it's possible that 1 or both of the plants (different strains, yeah I know, really smart) has decided to stop being hungry, but they're both still bulking up in the buds so I would not think that to be likely.  They are going through around 7 litres/day between them.  Also had a quick look with a torch and noticed a little bit of leaf tips curling down and under on 1 plant.

 

I'll try and find the time to flush more thouroughly again tomorrow, unfortunately I can't block the outlet to let the perlite soak for a while after some recent plumbing changes.  Feeling very stressed about this as these 2 plants are showing potential for good yields, so it would be a big loss if it all goes horribly wrong :crybaby: , these will give me a good buffer against outdoor crop failure, not to mention the potential hash production from excess buds.

 

Still open to thoughts or advice.  Any more probs/observations, I'll add them here, or if it all sorts itself out, I'll post the positive results in the grow diary

Link to comment
Share on other sites

Any chance your ec meter is screwy?

 

Like 3.4... can that be right? Might as well have the plant sitting in sea water or something. :unknw:

 

Possible, but I don't thinks so.  That was my first thought, but it's measuring tap water and other already mixed coco nutes at the normal levels, ideally I would use some sort of buffer solution like for the PH pen, but that's good enough for me.  But yeah, 3.4 near made me crap me daks.  It's times like these I'm glad I've got the tools, and I'm using them, don't even want to think about the potential damage of leaving that unchecked

Link to comment
Share on other sites

I just read this which I didn't know:

 

 

The conductivity of a solution is highly temperature dependent, therefore it is important to either use a temperature compensated instrument, or calibrate the instrument at the same temperature as the solution being measured. Unlike metals, the conductivity of common electrolytes typically increases with increasing temperature.

 

http://en.wikipedia.org/wiki/EC_meter

 

That could at least explain small fluctuation I guess.

Link to comment
Share on other sites

Could certainly explain a small fluctuation, possibly the rise since the fresh solution after flushing, as it would take the water heater a couple of hours to get 45 litres up to mid 20s.  It will be interesting to see where it's at in the morning.  Possibly nearly warm enough to stop using the heater, I was certainly going to take it out for the last couple of weeks in an attempt to encourage some blue/purple colours into the buds.

 

Anyone aware of anything easily obtainable that can be added to water to help dissolve salts etc during flushing, that doesn't harm the plants.  Was going to run a couple/few lots of water through over several hours and hope that gets everything, but I'd be happy to play it safe.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

By using the community in any way you agree to our Terms of Use and We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.