# Another DIY 4*dkh Solution



## jcgd (Feb 18, 2004)

Wow. That's so easy. I might have to try that.


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## Cardinal's Keeper (May 19, 2012)

Please do, it would be good to know so the process can be proofed


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## sayurasem (Jun 17, 2011)

Hi, I wonder if you live local. I live in the Inland Empire. Maybe you can sell me some of that water?


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## Cardinal's Keeper (May 19, 2012)

In laguna niguel. 

I have a couple 3oz bottles ready to go.


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## Hoppy (Dec 24, 2005)

That is a very good method, even though I didn't try to check to see if it should be accurate. The good part is that everything is measured in large enough quantities to do accurately, and then it is just dilute, dilute, dilute. Lots of waste, but baking soda is cheap.

May I copy and paste this in the sticky in the fertilizing forum?


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## Cardinal's Keeper (May 19, 2012)

Go right ahead Hoppy

And yes, quite a bit of waste water and overall solution when completed. But to err on the more accurate side is why I went with the amounts I did. One could half all these measurements and end up with less waste/product, but as mentioned I prefer to work in larger quantities.


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## In.a.Box (Dec 8, 2011)

Nothing is waste since you going to run it through the RO anyways.
Wouldn't that removed the baking soda that was add to it?

I'll give this a shot once I pick up some Di water.


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## Hoppy (Dec 24, 2005)

It goes through the RO filter before the baking soda is added, so no, it doesn't.


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## PlantedRich (Jul 21, 2010)

New guy question?? Is RO , distilled and 0 TDS water the same? Does the "quality" of distilled water vary? 
If I'm totally confused please feel free to correct me. I'm confused a lot these days!!! 
Love the method as it sounds so much better and more workable for me.


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## Hoppy (Dec 24, 2005)

RO/DI (reverse osmosis/deionized) water is about the same as distilled water - you probably couldn't detect the difference. Zero TDS (total dissolved solids) is a measure of what is in the water, not a method for achieving that - distilled or RO/DI will very likely be 0 TDS. The goal with making a KH standard solution is to have nothing in it that affects pH except carbonates/bicarbonates and CO2. Distilled or RO/DI would both work, assuming they were properly done. And, if they aren't perfect, the water is still good enough for what we need.


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## aunick0308 (Mar 18, 2008)

For over 11 years I have worked as a lab analyst at an environmental testing lab. When I first started working at the lab we would make our own DI water, but we started having some issues (can't remember what they were) and so we started to just use store bought distilled water instead of making our own DI. We also use jugs of water that is labeled purified water as it is the same as distilled. We have used both name brand and store brand, and I have never noticed a difference in the quality.


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## PlantedRich (Jul 21, 2010)

Thanks for the info. Sometimes I had assumed that to be the case but then I find I need to check things and not just take while APPEARS to be right. I think I will do this and check the two solutions against each other. My first attempt at using weight seemed to have sever choices where the best I could get was "close nuff". Don't really like to work that way even though I know that the final color answer is still just an estimate to figure in with other information.


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## Cardinal's Keeper (May 19, 2012)

Glad to hear you will give it a shot!

But mind that unless you are able to verify that you are starting at 0 tds or damn close, results cannot be guaranteed. I found that if tds rose to around 74-76, it threw of the dkh slightly. 

When I was working in a lake biology lab, seemed they would get lazy on the ro filter maintanance. Wonder if that's what issues your lab had also, Lol.
Sent from my Kindle Fire using Tapatalk 2


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## PlantedRich (Jul 21, 2010)

Quote "results cannot be guaranteed." 

I have found that in this hobby, that is part of the challenge! If I find some advise of this sort which IS guaranteed, I tend to suspect the offering!!! Waaay too many options for screwing up the process. 

Thanks again and I will offer up what different results I may find. 

Just one of many small decisions to think over.


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## Cardinal's Keeper (May 19, 2012)

Haha! Yes very true, just trying to limit the variables which could result in the method not producing predictable results. 

The only place I "guarantee" predictable results is in my own garage "lab", lol


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## fahim6801 (Jun 1, 2012)

nice job, i have a question, is the solution that came with the drop checker is 4dKH solution?? and u suggesting us to make this solution so if the solution that came with the drop checker is done using we can use this diy solution........... or do we need to add this solution with the one that came in the package im new in drop checker, bought one last week but dont know how to use  hope to get some suggestion


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## PlantedRich (Jul 21, 2010)

I'm not sure what comes with the drop checker. Never bought one. But this is to make a solution that is 4dKH. Then we need to add the "PH indicator solution" Which comes with API test kits. That turns the solution blue. When exposed to the CO2 coming off the water, the blue will slowly turn yellow if CO2 is low or green if near the 30PPM we consider correct. There are several items here that will explain far better but it may take some searching to find them. 

Any directions with the drop checker? Seems they should tell you something like that!!!


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## jcgd (Feb 18, 2004)

Blue < Green < Yellow
Less co2 ---- More co2


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## Bryanmc1988 (Apr 3, 2012)

so how do you use the kh to test the diy 4dkh mix?


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## Hoppy (Dec 24, 2005)

You can use twice as much water in the KH test tube and each drop of the reagent equals 0.5 degrees of KH, making it easier to determine that the KH is 4 and not 3.5 or 4.5 dKH. Of course this means assuming that the test kit reads accurately, and if it is more than a year or so since it was manufactured, it might not do so.


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## newbieplanter (Jan 13, 2013)

Cool beings I gotta try this.


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## don.dagg (Jan 10, 2013)

Wow, by saving the splits, you could have 24 cups of the stuff and only discard 4 cups. That is a bunch of 4dkh! And less waste.


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## pgaron (Oct 25, 2013)

This thread is amazing and I think is well worth a sticky


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## CSlater21 (Sep 26, 2013)

Thank you very much for this. Made a batch today and worked perfectly. Have some extra if people want to buy.

Sent from my SM-N900T using Tapatalk


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## dzega (Apr 22, 2013)

what should chineese TDS meter read when im at 4dKH solution using baking soda and DI water?


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## Cardinal's Keeper (May 19, 2012)

I have no idea but I can't think why a Chinese TDS meter would be any different than any other TDS meter. There all made in China anyway..


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## dzega (Apr 22, 2013)

Cardinal's Keeper said:


> I have no idea but I can't think why a Chinese TDS meter would be any different than any other TDS meter. There all made in China anyway..


should it be 70ppm then?


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## narayanan (Mar 19, 2014)

Hi, thanks for the great article...
I have a doubt here.. I have Co2 drop checker bulb, i can prepare 4dhk solution using the above mentioned method, now what about the PH indicator solution that turns the liquid color to blue. How to prepare that solution or is there any way to test co2 level only using this 4dhk solution?? ..


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## Onyx165 (Jul 16, 2013)

narayanan said:


> Hi, thanks for the great article...
> I have a doubt here.. I have Co2 drop checker bulb, i can prepare 4dhk solution using the above mentioned method, now what about the PH indicator solution that turns the liquid color to blue. How to prepare that solution or is there any way to test co2 level only using this 4dhk solution?? ..


The indicator solution is called bromothymol blue. Its what comes in an API pH test kit. Just add a few drops of that to your 4dkh solution in a drop checker, and you're good to go


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## Hoppy (Dec 24, 2005)

There are instructions for making your own indicator reagent, from bromothymol blue dye, on the internet. It makes no sense to try that if you can buy a good pH test kit that uses that type of reagent, because we use only a few drops at a time. But, I know you can't buy a good pH test kit everywhere in the world.


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## Aquaticz (Dec 26, 2009)

Hoppy wrote this- I saved it - here it is again 
Hoppy wrote 

It looks like any of the drop checker varieties will work as well as any other. The most effect the differences would have is in the response time, and that seemed, in my testing, to be about 2 hours no matter what the differences in design were. 

The solution to use in the drop checker is water having nothing in it that affects either the pH or the KH other than carbonates/bicarbonates. The easiest way to do that is to use distilled or DI water and add sodium bicarbonate (baking soda) to get the KH you want, which is 4.0 if you want the solution to be green at 30 ppm of CO2 or 5 if you want it to be green at about 40 ppm, which is almost too high, in my opinion. The accurate way to get a known KH is to weigh dried bicarbonate of soda and add an accurately weighed amount to an accurately measured volume of distilled water to give ten times the KH you want, then mix an accurate amount of that water with 9X as much of distilled water, which will give the desired KH. For the amount of dried sodium bicarbonate to use, add 4.99 grams to 5 liters of distilled or DI water. This makes 40KH. Add 10mls of this to 90 mls of distilled or DI water to make a 4KH solution. Then add enough drops of pH reagent to get a strong blue color, but still transparent. It is best to do this only to very small quantities of the 4dKH water, not a big bottle of it. 
__________________ 
Hoppy 

http://www.aquaticplantcentral.com/forumapc/sacramento-aquatic-plants-society-saps/part 2 

This is a setup of two bodies of water with a air passage connecting them. CO2 goes into solution and out of solution very easily, so there is a constant flow of CO2 from any body of water and the air in contact with it, going both ways. This means an equillibrium must be reached, where as many CO2 molecules enter the air (or water) as leave it. So, two such bodies of water will both reach equillibrium with the air passage connecting them and both must have the same ppm of CO2 for that to be so. If one body of water changes in CO2 concentration, that changes the amount of CO2 in the air passage contacting that water, and that change then changes the CO2 concentration in the other body of water until it is equal to the first one. All of this takes place pretty slowly, like over an hour for equillibrium to be reached. 
__________________ 
Hoppy 


Wet wrote this ....

From wet's site 

Reference KH for target CO2 calculator 
1) Add 451.9 mg of baking soda to 1 Gallon of DI water for 4.0 dKH. Fully dilute. 
2) Add the contents of this mixture to the drop checker, then add a couple drops of Bromothymol blue to the drop checker. 
The range for "green" in this drop checker is 18.9 - 47.5 ppm CO2. The perfect green (shade, reaction between Br. Blue and CO3) is 30.0 ppm CO2. 
Top of Form 
My target CO2 is [Control]ppm 
I have a [Control][Control]Liter [Control]Gallon container to mix with (recommend at least 2L) 
I have [Control]one [Control]two drop checkers. 
[Control] 
Bottom of Form


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