Does the pH setting give accurate results in a Kh 0 system?

[Naturescapes_Rocco]

Just to be that douche bag, I wish my Macandra yellow was actually yellow at 30/10/40 with .45 Fe. Maybe I was sold something different, but damn limitation had no play in keeping it red.
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Is the center-red plant Rotala blood red?? How is it that red at those macros!

Edit: or am I an idiot lol is that the Macrandra? What is the pinkish plant foreground right?

Edit Edit: Ok, I got all the info I needed from your AGA Entry Never mind!

 

[Burr740]

Hi Joe,
I've wondered before about this. Apart from fish health, what negatives might you expect to see with C02 being too high?

I hesitate to assign anything specific, various plants just start doing poorly, stunting or otherwise get unhappy. Sensitive things first but others too. The whole tank would just get in a not-right state. Random algae pops up, plants not looking great, water would lose the crystal clarity it has when a tank is really doing good. That sort of thing

It wasnt always dramatic, usually more of a slow decline over a few weeks. Ive tried really high levels many many times in different tanks. Im pretty sure it brought on the dreaded "droop and die" syndrome in Rotala Sunset, twice

 

[mrtank50]

Yes everyone, thank you for all your replies. Unfortunately, I couldn’t respond earlier. I waited for the CO₂ test kit to arrive. According to the CO₂ test kit, the CO₂ level was measured at an average of 55–56 ppm. Additionally, the daily NO₃ dose I was giving was 0.9 ppm. I increased this to 1.2 ppm, which is only a 0.3 ppm increase. I was also dosing 0.11 ppm of K daily, and I increased this potassium dose to 0.6 ppm per day. All other parameters remained the same.


Under these conditions, Rhizoclonium algae exploded even with only a 7-hour photoperiod. This was honestly a very interesting experience for me. However, the plant paleness did not resolve. At this point, I started to think that increasing potassium caused an increase in NO₃ uptake, which drove NO₃ down to zero, and this benefited Rhizoclonium. The next day, I plan to try adjusting CO₂ to around 30 ppm and dose only 1 ppm of NO₃ using MgNO₃. In my opinion, this chlorosis issue is related to NO₃.

 

[Burr740]

That is too small an increase to do anything, or to deduce any causation. Dry dose 10/3/15 to get the levels up. Then do a couple ppm NO3 daily with the rest increased proportionately. Give it two weeks, and ignore anything that happens in the first few days. Plants will have to adjust their inner workings from survival mode in a famine to having enough of everything. Guarantee you that will fix things

 

[mrtank50]

That is too small an increase to do anything, or to deduce any causation. Dry dose 10/3/15 to get the levels up. Then do a couple ppm NO3 daily with the rest increased proportionately. Give it two weeks, and ignore anything that happens in the first few days. Plants will have to adjust their inner workings from survival mode in a famine to having enough of everything. Guarantee you that will fix things

I will apply what you said this week. What should the Ca and Mg levels be in ppm? Also, according to these ratios, what should the Fe level be in ppm?

I am preparing a mix of Fe DTPA (7%) and Fe gluconate. If you tell me the target Fe ppm according to that, I will dose accordingly.

 

[Burr740]

30-35 and 5-10 are good general ranges for Ca and Mg. There's a lot of wiggle room with those but you wouldnt want to be much lower

Dosing those macro numbers Id run micros at about .4 ppm Fe per week, plus or minus .05 would have you in a good range

This is basically 14 ppm NO3 per week. Ignore the 10/3/15 front load. Thats a one time thing to get the levels up to an adequate baseline

Personaly I dont like daily dosing macros when doing more than 30-35% water changes. Because theres too much of a drop in nutrient levels during the first few days of the week. Changing 50% or more I like to go 3x per week, with some of it front loaded

The macro routine Ive stumbled on these last few years that works great:

Doing 50% water changes, front load 50% of the weeks total right after the wc. Then split the other 50% in two doses on through the week

Changing 70% of the water, front load 70% of the weeks total right after wc, split the rest in two doses, and so on

At 50% or above, whatever percent water changes youre doing, front load the same percent of the weekly macro totals

On low dosing macros in general - Unless your set up specifically for low dosing with a fresh rich substrate (new aquasoil), macros need to be in a certain concentration in the water in order for the plants to get what they need. You cant roll with zero levels and just dose what the plants uptake, like 1 ppm or two. It doesnt work that way. Plants can get the 1 or 2 they need easier if theres 20 in the water, for example

Micros CAN be dosed in small dribbles as the plants need them. They dont need any baseline concentration. Its only for the macros including Ca and Mg

 

[Unexpected]

Is the center-red plant Rotala blood red?? How is it that red at those macros!

Edit: or am I an idiot lol is that the Macrandra? What is the pinkish plant foreground right?

Edit Edit: Ok, I got all the info I needed from your AGA Entry Never mind!

Not sure how I missed this reply. Yes, the Rotala behind the Blyxa is the blood red variant. The right foreground is the Macandra. I bought it as a yellow version but maybe it's not. I've found the best colors come from well fed happy plants.

 

[tjcline0]

Is the CO2 released by a 1 pH decrease in KH0 equal to the CO2 released by a 1 pH decrease in KH4?

The answer is no. The chemistry is pretty simple.

KH, or carbonate hardness, is a pH buffer in your aquarium. It makes the water more resistant to changes in pH. As CO2 dissolves, some part of it becomes carbonic acid. This then reacts with carbonate/bicarbonate ions in your water, effectively mitigating some of the acid addition. So when KH is 2-6+ then 30ppm co2 will only result in ~ 1 pH drop. In a KH <2 scenario pH might drop 1.5-2.0 from the same 30ppm addition, because there are no buffers to absorb carbonic acid. KH/pH/CO2 can be inaccurate when other acid/base reactions are present that interfere with the fundamental acid/base reactions.

Soft water is great, but I like to run KH ~2 to reduce the amplitude of pH swings.

 

[Marwen]

KH, or carbonate hardness, is a pH buffer in your aquarium. It makes the water more resistant to changes in pH. As CO2 dissolves, some part of it becomes carbonic acid. This then reacts with carbonate/bicarbonate ions in your water, effectively mitigating some of the acid addition. So when KH is 2-6+ then 30ppm co2 will only result in ~ 1 pH drop. In a KH <2 scenario pH might drop 1.5-2.0 from the same 30ppm addition, because there are no buffers to absorb carbonic acid. KH/pH/CO2 can be inaccurate when other acid/base reactions are present that interfere with the fundamental acid/base reactions.

Soft water is great, but I like to run KH ~2 to reduce the amplitude of pH swings.

That's a common misconception.

If for example the water has 3 ppm dissolved CO2 with no CO2 injection, it would take a 1 pH drop from CO2 injection to reach 30 ppm CO2 regardless of KH.

So adding KH will not reduce the amplitude of pH swings caused by CO2 injection. It will merely move your "degassed" and "gassed" pH upwards, while the "swing" remains the same.

As such, the only reason you may want to raise KH in a planted tank is to move your average pH into a place that is needed for some livestock that you are raising. Since plants don't care. (All plants care about as far as pH goes is its effects on nutrient availability, especially micronutrients.)

 

[Naturescapes_Rocco]

I agree with you until you get to 1KH or lower.
At just 1 dKH , total alkalinity = 0.36 meq/L. The bicarbonate concentration is tiny. At a low KH like this, the water has almost no buffering capacity and even trace acids or bases cause large pH shifts, or certainly way larger than at any KH >2.

So at these super low KHs the pH you measure becomes influenced by:

• Humic & fulvic acids
• Nitrification acids
• Organic decay
• Phosphates
• Silicates
• Measurement noise itself

Once those start competing with carbonates, the CO₂ tables lose their predictive power and the 1.0pH drop becomes inaccurate. I've tested this countless times and posted about it frequently. I fully agree with you with other KHs, but not at KHs around/less than 1 (which is where all of my tanks sit!).