Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

Considering our especially hard water, I'm surprised that there doesn't seem to be a discussion about water hardness in the AZ group (unless I missed it).

From what I've read most people in general (not locally) do not like RO filtered water, but people with really hard water (like us in Scottsdale, pH 10+, hardness of 1100 ppm with EC meter, still waiting for my KH/GH test kit to arrive) should use an RO filter, right?

Is that what most people in the valley do?  Anyone have specific recommendations for RO filters?  

Thank you.

Views: 607

Replies to This Discussion

I think most people treat their water with muriatic acid(pool acid) to get the ph down.

Personally I gave up on messing with it, and just let mine sit at 8.0.

Since most established systems will naturally, due to chemical and biological processes, drift lower in pH, I have found that the high pH water is actually beneficial, since I rarely have to add pH buffers to my system.

On occasion I will add some muriatic acid (pool acid) as needed.  I did so yesterday as the pH had risen to mid 7s, but it's not something I watch all that closely.    If I've done a lot of top up, I'll check the chemistry, but other than that I let nature take its course.  It was only a couple of weeks ago that the pH was getting a little low and I added some potassium bicarbonate, but that was also to provide some much-needed potassium to my flowering and fruiting plants.

I aim for a pH of 6.8 but don't get too flustered if it drifts +/- each side of that.


My experiance with RO filters showed the large volume of wasted water resulting from the self cleaning process in the system. With my 1500 gallon system the added water loss would be significant.

I had a salesman demonstrate a process which caused all of the suspended solids to preciitate out of the water. It was dramatic but I can't remember the company name. Zero water or pure water sound familiar. The company was in the Tempe Mesa area.

Tony:  Check your test kit. 

Scottsdale runs about 8.2-8.3 

check this page out:

I, like others with mature systems, has turned a blind eye to pH.  didn't seem to make all that much difference in my system...

Thanks everyone for your input.  I guess I won't worry about it, although I do have access to a small RO filter so maybe I'll use half RO water. 

Jim I was expecting an aquaponics-related link, I see they mention ph but I don't see the connection?  Or are you just pointing out that a ph of 10 kills everything?

Jim I don't think I let the water stabilize before I tested it so I'll try again.  Despite everything I've read (that soilless plants only absorb nutrients at very narrow ph bands) what you said seems to hold true for most people---they don't worry too much about the ph.

I also thought I saw that really hard water was bad for fish...

No, RO pulls all the minerals out of the water and both plants and animals need minerals. The water hardness is not much of a problem except 1. as it relates to PH and 2. accumulated minerals/salts. The PH in new and small systems can be controlled easily with muriatic acid, but larger and matured systems self-manage PH. The accumulated, but not used salts/minerals can be managed through an annual or semi annual water change. I don't personally know anyone who has had a problem with that yet, but the problem does exist in theory, and maybe someone has run into that problem.

BTW, the highest PH I've heard of here in AZ is 8.4, which is plenty high!  Are you using the API test kit to measure?

Haha! I saw no answers, so I answered, and now I see many!  So sorry for any redundancy!


If you look at that chart below you will see that all the minerals are available at both the gray and black lines which represent 6.5 (the holy grail of AP) and 8.3 Arizona's natural pH.  I run my system around 8.2 because it has a preexisting cement fish pond which is a big no no in AP.  The only reason I can figure it is verboten is because you can't achieve the holy grail 6.5 - 7.0 pH.  However, everything grows well.  I may add a little more mineral supplement for the metals than other AP growers do but who really knows for sure?  This is after I had created a pile of empty pool acid bottles.yes, the point of that link was nothing survives a pH of 9 or 10.

@ Sheri: we love to hear from you anyway...

cmwyhnc  ;-)

Well that was a rookie mistake, I didn't look closely enough at the test kit.  I thought it maxed out at 10, it maxes out at 8.5 so I just read it wrong and my water is 8.3.  

Sheri: I was using the Gen Hydro liquid wide range ph kit, now I also have the API test kit.  Thank you for your feedback.

Jim: That makes sense, thanks a lot for laying it out for me.

From what I saw on the gov website, Scottsdale water only contains chlorine, and does not contain chloramines?


So does anyone know if that's true for hydroponics as well, or is there something special about AP?

I know in theory the chart Jim posted applies to hydroponic gardening as well and it should work.  But I guess I'm wondering if anyone's had hands on experience---have you grown anything hydroponically with water straight out of the tap (after you degassed the chlorine, of course)?  I mean no ph or hardness adjustment.

Hi guys...the chart that Jim posted actually applies to soil gardening and not hydroponics (or any other type of soilless culture). It is common to mistake the charts as the two are often floated around "internet-land" rather indiscriminately :)

Most (decent) soils have a vastly different cation exchange capacity than most common soilless mediums...or "worse" yet, water culture (as in a DWC scenario, this is why, in part, in a low nutrient density environment, or one where pH is rather high, plants in the DWC portion of a system tend to exhibit visual signs of deficiency before their counterparts that are in a media filled grow bed...even though they are in the same system) below are two charts (soil vs soilless) for comparisons sake...

 Notice that the soil chart is much more forgiving...

Oh, and no...there is nothing "magical" about AP. How plants grow without soil, is how plants grow without soil. That said, a well seasoned, mature, micro-biologically thriving AP system seems to display more of that "soil like" forgiveness, that a new or micro-biologically sparse one (much of this seemingly has to due with niche nutrient cycles beyond ammonia oxidation) .

RO filters waste a lot of water on the flush cycle.


© 2024   Created by Sylvia Bernstein.   Powered by

Badges  |  Report an Issue  |  Terms of Service