kH/CO2 variance with seasons

[original kuhli]

I think I may have put the original post in the wrong forum, nonetheless here's a link:

http://www.plantedtank.net/forums/al...e-seasons.html

[Sponsors]

[@marko@]

that sucks. my kh is even all year round. most of the water from my area is from aquafiers, some from lakes (which are spring fed, and the springs are fed by aquafiers).

[original kuhli]

Additional post here:

http://www.plantedtank.net/forums/al...tml#post600579

[mistergreen]

the TDS may vary but I don't think it affect CO2.
The KH,PH,CO2 chart is only a rough guestimate in very controlled conditions.

It's like saying you just raised you CO2 by adding in Baking Soda to raise the KH. Obviously, you need to inject CO2 to raise CO2 levels.

[original kuhli]

Not true, the adjustment of pH versus CO2 is based upon the kH of the water. A given CO2 depression of pH at one kH is not the same amount of CO2 as at another kH.

[mistergreen]

then shouldn't the PH in your water change as well?
The only fluctuation is the KH. Just seems like the levels of CaCO3 varies and that's it.

try putting a drop checker in your water and compare it to the chart.

[original kuhli]

I'm a bit confused by what you're saying, at a given kH a set amount of CO2 will depress the pH a given amount, if you vary the kH the same amount of CO2 will not move the pH the same amount because the relationship is logarithmic.

Practically speaking the changes in kH matter immensely because I run the risk of either over or under dosing CO2 resulting in algae or dead fish. Am I missing something?

[plantbrain]

Since you want to discuss seasonal variations:

Temps, when it gets 100F outside and the tank temps go up from say 78F during the winter to 85-90F, what happens to the rates of growth,the amount of O2 demand from bacteria?

They go way up, maybe 20-%. maybe 40-50% even.

If you added say 2 bubbles per second of CO2 when it was cool, what happens now?

What about O2?
Fish metabolism?

These things can change a fair amount when the temps go up.
KH typically goes up the longer you go without rain for surface waters.
Wells should be fairly constant. But not always.

Warmer water also holds less gas at equilibrium.(all gases, O2 and CO2 etc).

Regards,
Tom Barr

[original kuhli]

Hey Tom, thanks for joining in the discussion, I think seasonal variances have a significant impact on our tanks and algae patterns, we just don't understand all of them.

In Calgary where our water is sourced from rivers that are less than 130km from the Rockies our hardness is predicated on runoff rates. The high runoff of spring/summer results is decreased hardness, and the very low runoff of cold winter results in some of our highest hardnesses.

Tank temps aren't too much of an issue here even without air conditioning although we do get into the 90's for weeks on end in the summer. Having said that I can see it being a pretty serious implication in many places that don't cool off at night or are just really hot.

I'm curious if anyone has ever seen a temperature corrected/sensitive chart of pH/kH/CO2?

There's also a pretty major consideration on how/if you're controlling your CO2 delivery and if its pressurized vs yeast based.

[plantbrain]

Temp and CO2 from yeast production is very understood.
No doubts there.

Plant growth rates and the influence of temp is also very well understood.
In general: more heat: more growth to about 35 C or so.

When you have higher rates of growth, clearly you will have more CO2 demand.
So if you have the same old CO2 bubble rate, but say 1.5X moire demand, this can lead to algae.

Even if you changed nothing.
The other thing is that folks observe their plants and tanks etc, they assume that the O2/CO2 remain the same, fish also metabolism at higher rates and behave differently, pretty much like you do when exposed to 70 F vs 100F.

This can affect the tank.

The other thing that folks generally over look when making tank to tank comparisons: the amount of plant biomass.

This can double in 2 weeks in some tanks, others? Months or longer.
Obviously if you have rapid growth and do not prune often, then you can have 2-3X more CO2 demand.

This is just common sense.

But many over look it and don't consider it.
They hear some clown who only adds a little bit of CO2 and they have no algae and they compare them as equals.

When plant biomass doubles or triples in an aquarium, you also have massive flow restrictions in the current and the patterns. So flows are generally reduced by 60-90% in plant beds vs a well trimmed tank.

They have measured the flows in and around plant beds in lakes, rivers and streams. The difference is massive(90% reduction is a typical range for most of the studies). This influences growth and exchange of nutrients and CO2/O2.

And if you mess with CO2, does not matter what the PO4/NO4/K and precise weekly monitoring and testing, subtle variations in your dosing routines etc.

CO2 is still the 95% of all algae related issues in every tank I've worked on, fix or helped someone deal with. And if you cannot get that right, you have no chance of confidently testing or determining much of anything with nutrients like NO3.

Now think about how to measure CO2 very critically(it's tough to get a precise timely measure)............now you have a making for a big mess and many theorist suggesting algae is caused by xyz.......

However, you can rule out nutrients by providing what you assume to be non limiting amounts, then a stable light intensity, then manipulate CO2 over a wide range and observe........that's where 30ppm came from and many others before me came to 40ppm or some about 25ppm etc, research suggested 30ppm etc.




Regards,
Tom Barr