Ok, one more time on KH

[John]

Apologies as I know this topic has been beaten to death but I am getting results that don't match most recommendations I find. 

My issue is one of low KH.   In my 180g indoor aquaponic system i use only pure reverse osmosis water salted to 1-2ppm.    I then add 50%  Hydrated Lime (calcium hydroxide) and 50% Potassium Hydroxide to settle the PH at 6.8.

It seems stable at this PH but drifts downward over a week or 2 which seems a bit faster than I would expect from what I've read. At which point I add a little more of the base solution to bring it back up to 6.8.     Plants are very healthy.  

GH is  125ppm ( or 7 dkh, 7 drops of test solution. ) 

KH is near 0.  (yellow on 1st drop.  but shows 40 on test strip. still low )

PH is 6.8 

TDS is 1430

temp 84F

Nitrate 5ppm

ammonia 0

nitrate 0

Ok. here's the big question:   I have read that I do not want carbonates in my system which is why I do not buffer with Calcium Bi-Carbonate.     KH does not seem to be impacted at all by my 50% each of Hydrated Lime (calcium hydroxide) and 50% Potassium Hydroxide.   So, am I buffering with the wrong materials?      If not, why is my KH not moving at all? 

Trying to follow Nate Storeys' advice along with many other forum posts and web sites.   https://www.youtube.com/watch?v=zP1rUMyklyc but am concerned about 0 KH. 

thanks!

 

[Vlad Jovanovic]

It's hard to say what "a lot" would be...even if we knew what strength HCL you were using (% in solution) 

[Glenn]

As an experiment this past weekend I borrowed 50 gallons of well water from a friend that measured 8.0 with his test kit in his barrel at his place.

I washed my barrels, pumps and system with bleach treated water then rinsed several times and dried thoroughly.

I transferred the borrowed sample to my barrel and circulated through an open air particle filter and measured 8.2 pH.

Then while circulating without filters about 30 minutes, I slowly added 15 drops (1/8th of a teaspoon) of tree fresh lemon juice.

Lemon juice should never be used except in a very small diluted fashion. I normally would have used about a 1/2 to 3/4 teaspoon of apple cider vinegar.

The friend I borrowed the water from told me quite some time ago to NEVER use lemon juice and to only use up to a teaspoon of lemon zest. He only recently began using it this way to treat his well water.

Anyway, after circulating another hour and letting it set covered  all of Sunday It read 7.2 ph this afternoon. I will run it through purification and mineralization/normalization tomorrow. I expect to use it in my system as make-up/top off water next week.

[John]

I didn't expect this thread to live on.      I am not an expert but for me, I gave up on the HCL (muratic) acid treatments to my tap water because it just didn't seem to last due to buffering no matter how much I treated it.   Then, I had a 50 gallon system and would add HCL to buckets of top off and let sit for a couple days.   I could not get the PH below 8 in my system no matter what.    Pain.  I moved to using R/O and mixing in a small amount of outflow of the RO to get some minerals back in after passing over the charcoal pre-filter.   Since then, I have not had to bring PH down, only up using... ( read above )   My KH is still too low but am slowing bringing it up with R/O waste water and potassium bicarbonate.      My system is very healthy so am goin with it. 

[Alex Veidel]

Good point :-p

I'm using a 31.5% HCL solution. It's taking three tablespoons to get 55 gallons down from 8.0 to 7.6. I'm also aerating these 55 gallon barrels. I use a 18% phosphoric acid solution to adjust my 600 gallon-ish system, which takes around 1 tablespoon to make a .2 adjustment, say, from 7.4-7.2.

It's either my water that's the problem or I just have an unrealistic expectation of hydrochloric acid....I really have no idea.

Vlad Jovanovic said:

It's hard to say what "a lot" would be...even if we knew what strength HCL you were using (% in solution) 

[Jim Fisk]

You guys with the tap water ph problems (not to mention fluoride and chlorine) ever check the local streams or lakes for ph? It might pay to have a 55 or an IBC in a PU or trailer and haul from those sources with a 12v or gas pump if the ph turns out to be more to your liking. With permission of course

[Alex Veidel]

Well, it's been like -20F (-28C) outside, so.... no, I haven't really considered that to be a viable option :P Closest water source is my neighbors pond, which currently is thick with ice and is always a tad on the nasty side anyway.

I'm using well water, so there's no fluoride or chlorine.

[Steve R]

Here you go http://theaquaponicsource.com/2014/02/02/the-carbonates-controversy... 

[Alex Veidel]

Thanks Steve :)

Steve R said:

Here you go http://theaquaponicsource.com/2014/02/02/the-carbonates-controversy... 

[Alex Veidel]

Tested my KH levels today...system water at 4dKH, pH of 7.6 and my well water, well... let's just say that after 12 drops, it stayed a VERY dark blue and never turned yellow. pH was 8.3

Does using a water softener adjust KH? And is using softened water taboo in aquaponics because of the salt? I've been bypassing my softener all this time....Or maybe I just need to find a new water source. I don't know guys.

[Alex Veidel]

Oh, and please assume I don't know anything in regards to water quality. New information is being added to my knowledge base and it's all kinda up in the air for me right now :/

[Alex Veidel]

Or maybe, I should just accept my high pH and go with an EDDHA iron chelate until the rain comes again.....

[Jim Fisk]

Yup, here too. Damn cold Winter. -20F just a week ago. SPRING!!!!!!!!!!!!!!!

Alex Veidel said:

Well, it's been like -20F (-28C) outside, so.... no, I haven't really considered that to be a viable option :P Closest water source is my neighbors pond, which currently is thick with ice and is always a tad on the nasty side anyway.

I'm using well water, so there's no fluoride or chlorine.