Is there a comprehensive chart that lists the "normal" range for the different water tests.

[Don Cole]

I am ready to start the cycling of my system. The system currently consists of two 4' x 8' grow beds in a flood and drain configuration (future expansion to 8 grow beds) and three 300 gal. fish tanks. Before I put fish through the torture of my lack of knowledge of water chemistry I would like to find a chart of what the norms should be for the critical aspects of maintaining the correct balance. 

I have done a lot of reading on the subject and there is a lot to comprehend. I am not looking for the science behind the different elements since that information is available from a wide variety of sources. I think a chart listing the different specific tests and the normal range for each would allow a system operator to quickly identify and research a solution to a potential problem before a catastrophic event occurs.

There are a ton of very knowledgeable people on this forum but not all of us are chemists or bio-majors and we simply need the facts from those that are chemists and bio-majors.

Thanks,

Don

[Michael Brooks]

Don Cole said:

Michael,

I agree with everythjing you said. That is the purpose for this discussion. I would like to create a list of the important basic variables that NEED to be monitored and thier values nothing else.

If you have the base numbers correct there would be nothing to worry about except counting your lettuce.

Don,

 Lol. That's right buddy!

 

[Don Cole]

These discussions evolve on thier own so no worries. I am getting the info needed and learning a lot along the way. Congratulations on your sucess, I hope to be there someday myself. My grandparents were farmers back east and I live in Phoenix Az. I have always liked to grow veggies and such but the climate is brutal here for most crops and space is a premium. I stumbled upon aquaponics about 8 months ago and have become kind of obsessed. I have built a 20' by 30' greenhouse and getting it fit up now. Hopefully I'll have something green in it by October.

I would love to see your operation in person. I am VERY interested in the commercial application of aquaponics and you dont hear of too many large sucessful ones. So, congratulations again.

[Matt H.]

You're right vlad, my k is undetectable on the cheapo rapid test kit( since I had to buy the multi test kit at$6 for two K tests it's actually not cheap at all except for results). My iron is also zero as I wait for chelated iron to arrive. I've been adding maxi crop w/ iron but it gets sucked up quick as can be.
Does anyone know of a decent potassium test kit w/o spending hundreds of dollars? All I've been able to find are the cheapo multitest kit for soil and a probe for over$300. I am concerned with my hardness test off the chart high, but just kind of holding back until I have Fe and K to dose and see if that starts bringing things into balance. />

Vlad Jovanovic said:

Well, I'm certain my answer isn't going to be as linear as "the chart" that folks were looking for, but...

1). You are not necessarily in "lockout range". 140 to almost 200 can be fine (especially for heavy fruiting plants).

2). Calcium should make up between 35%-55% of the total cations (positively charged plant essential elements) floating around in solution in your system water.

3). All these cations (K, Ca, Mg, Zn, Mn, etc...) must coexist in a ratio'd balance since they behave antagonistically toward one another. So if your K is near 300ppm and Mg near 40ppm blablabla...Ca at 140ppm is perfectly fine. BUT

4). I'm betting if you test your waters K content it will be really low (in the double digits instead of near or above 300ppm) in which case 140ppm of calcium present in solution can be excessively antagonistic towards K as well as Mg uptake and exacerbate lockout issues.

You had asked about:

Mg - near 30ppm

Iron - 0.75 to 2ppm (Iron is the ONE cation that isn't antagonistic towards the others, so too much won't cause lock out issues, but good chelated iron is expensive so being wasteful just hurts the pocketbook)...

Phosphorous and phosphates is kind of a tricky one in a system where plant essential elements are derived from organic waste materials. Most common phosphate checkers can only check for orthophosphates (reactive phosphate) and not organic phosphates (you would have to perform a hot acid digestion test for that)...but look for P in the 3-10ppm range (or higher)...

but again, it's more about balance. Nature provided for a wide parameter of upper and lower limit thresholds for most of these elements so as long as things are somewhat in balanced and you haven't hit a limiting factor, things work pretty well.

Cheers,

Matt H. said:

Thanks Michael. 40-70 ppm calcium. That was a number I was looking for. I'm at about 140ppm. Do you think I'm in lockout range? I have some deficiency/lockout issues going on. Plants are growing but showing some crumpled leaf. How about iron, magnesium and phosphate levels?

[Matt H.]

Add to the list but realize these numbers aren't set in stone. Balance and stability are potentially more important than rigid adherence to the numbers.
Mg 30ppm
Fe .75-2.0 ppm
K 300ppm
P 3-10ppm

Don, I think we're getting somewhere now.


Michael Brooks said:

Alkalinity 50-250 ppm

Ammonia 0-.4 ppm

Carbon Dioxide 0-30 ppm

Chloride 0-5000 ppm

Oxygen 3-10 ppm

Nitrite 0-.8 ppm

pH 6.3-7.2 ppm

Calcium 40-70 ppm 

[Don Cole]

This is perfect!
I am going to compile these numbers into a spreadsheet to log my testing. I know there is more to these systems than numbers and I don't want to take the fun out of it.

Guys, thank you for all of the help.

[Vlad Jovanovic]

1). Yes, there are "ideal" ppm's for every element, for every particular plant in every particular phase of growth. The ideal ppm's for lettuce are quite different than ideal ppm's for cucumbers...which is why you will likely get many different answers from people on that question, depending on what they happen to be reading (since most people don't actually test for those levels...

2). They are all important, as one element alone can become a limiting factor...but K and Mg are the two biggies there...especially K

3). No, control of one won't really "keep the others in line".

 

Don Cole said:

OK, this is good stuff!

Vlad, from your reply the two items below state that there is a "antagonistic" relationship between the cations.

Is there an ideal ppm for each K,Ca,Mg,Zn,Mn? 

Is any one more important than any other to control?

Are there one or more of these that if controlled would keep the others in line?

Thanks for your help!

 

2). Calcium should make up between 35%-55% of the total cations (positively charged plant essential elements) floating around in solution in your system water.

3). All these cations (K, Ca, Mg, Zn, Mn, etc...) must coexist in a ratio'd balance since they behave antagonistically toward one another. So if your K is near 300ppm and Mg near 40ppm blablabla...Ca at 140ppm is perfectly fine. BUT

[David]

Great discussion and information here. Thank you to all. As my small backyard system matures, I find myself curious about testing for different minerals as discussed here. I use an API Pondmaster test kit for the basic "keep your fish alive" stuff, I also invested in a pocket pH meter and a dissolved O2 meter. I'm not sure I trust the pocket pH as I often test with the API kit and get different results (yes I have 7.0 calibration solution).

If anyone has recommendations for affordable test methods for specific ions / minerals (K, Mg, Fe, etc.) I would love to find out more. Even more expensive professional recommendations are useful.

I also test GH at almost 300 with KH at 20. I'm trying to find ways to reduce the GH and bring up the KH. My source water is a problem (tap water at high GH). I have rainwater available but I'm concerned about contaminates from my roof / environment so I run it through an RO filter which is a slow process, so not practical for large water exchanges.

Open to suggestions. Thanks!

PS:

My system is a 200 gallon IBC with 100 gal sump, 170 gal media beds, 18 catfish 10 - 12". pH low 7s, ammonia, nitrite and nitrate show zero across the board. Tomatoes producing well but severe leaf curl. I was using a UV light for several weeks until I read about depleting boron, etc.

[David Marland]

I have the API kit mentioned above plus the GH/KH kit. But watch Silvia’s clips on how to use them, I tested my system every week for six months. Then one week I started to get high levels off nitrates, I was doing the test wrong! Thanks Silvia for the new clips!

Ps. don’t leave your test kit in the sun! I am on my second test kit now,