# KH of 260ppm-unhappy fish!



## Adam S (Jan 28, 2006)

I have a 60 gallon aquarium with mostly sword plants, 4 wpg with T5s, CO2 injected with Milwaukee regulator and dose with Greg Watson ferts. This tank has seen a phenomenal turnaround since I began dosing with Greg's ferts (with the exception of BGA which is slowly going away) so I decided to add fish. The really durable ones have done well (the Otos and SAEs) whereas other fish seem miserable. Their gills pump like mad, especially in the am. Sometimes they are gasping a the surface as well in the am. Here's the tank's daily routine.

Lighting
2.4 wpg from 11:00pm to 8:30pm
4 wpg from 2:00pm to 8:00pm
*I used to run 4 wpg from 11-8:30; however, find that the tank's high temp 
is 84 rather than 86 degrees f. 

CO2 dosed at 2 bps from 10:00am to 5:00pm
*Pearling begins around 3:00pm and is massive from 6:00pm to 8:00pm.

Am Ph (before CO2 and lights) 6.9 or 7.0
8:30pm 6.6 or 6.7

I figured that the pumping gills were due to excessive CO2; however, at two bubbles per second I shouldn't be seeing this in the fish. According to a Dupla CO2 sensor I'm low on CO2. 

My next guess was hard water; purchased a LaMotte KH kit. Low and behold my water is 260ppm! With a Ph of 6.8 my aquarium has a CO2 level of 69 ppm!!! No wonder they can't breath. 

Two thoughts, one should I soften the water-if so any suggestions. Two should I cut back on CO2 injection to increase the Ph?

The plants are the focus here not the fish; nonethless they're manditory to my wife.

Any help is appreciated.

Adam


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## yznj99 (Oct 17, 2006)

CO2 concentration and KH are unrelated, although your tank pH is a direct result of CO2 conentration and water KH. 
Take a sample of your water, let it sit for a day or put an air stone in and bubble for a few minutes, measure the pH of this sample (it's a good idea to have a pH meter for this)
Now measure your tank pH 
if the tank pH is 1 unit lower than the original pH, your CO2 is around 30 ppm, that's the perfect amount
Adjust your CO2 bubbling rate until you have 30ppm of CO2
More CO2 will harm the fish, low CO2 you are asking for algae.


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## bharada (Apr 17, 2004)

High water temps = less dissolved O2 in the water.

Simplest solution is to run an airstone during the lights/CO2 off period.

Also, how tighly covered is your tank? I find that since I went open top on my tanks that they're a lot more forgiving with high CO2 levels. With a sealed top any CO2 that outgasses is trapped at the water surface, so even surface rippling will do little to aerate the water at night.


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## Adam S (Jan 28, 2006)

bharada said:


> High water temps = less dissolved O2 in the water.
> 
> Simplest solution is to run an airstone during the lights/CO2 off period.
> 
> Also, how tighly covered is your tank? I find that since I went open top on my tanks that they're a lot more forgiving with high CO2 levels. With a sealed top any CO2 that outgasses is trapped at the water surface, so even surface rippling will do little to aerate the water at night.


I have a canopy which covers the tank on three sides with the light about five inches above. I'm going to put a 90mm fan on this weekend for this purpose and hopefully to minimize aquarium temp increases from the T5s.

I've also thought about running an airstone at night; the Ph swings are my concern for the fish.

Adam


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## Adam S (Jan 28, 2006)

yznj99 said:


> CO2 concentration and KH are unrelated, although your tank pH is a direct result of CO2 conentration and water KH.
> Take a sample of your water, let it sit for a day or put an air stone in and bubble for a few minutes, measure the pH of this sample (it's a good idea to have a pH meter for this)
> Now measure your tank pH
> if the tank pH is 1 unit lower than the original pH, your CO2 is around 30 ppm, that's the perfect amount
> ...


I'd thought that the most reliable way to determine CO2 content was with the Kh? Actual Ph of my water source is 7.5 so I think I'm about where I need to be regarding CO2 input. There's a really good chance that the aquarium temp is the core problem and it's inability to hold O2 and a low of 81 and a high of 85. I'm putting a small fan between the surface and the lights this weekend to assist here.


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## Newt (Apr 1, 2004)

The attached chart may be of some aid to you. 

The tank temp is too high.

An RO system would be in order.


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## banderbe (Nov 17, 2005)

Your tank is too hot.

You'll find your plants grow much better between 72F and 78F degrees.

I shoot for 76F.


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## BryceM (Nov 6, 2005)

Adam,

A couple of points here...... The previous posts have touched on a couple of these.

A very common point of confusion is the relationship of O2 and CO2 in the planted aquarium. Both gasses dissolve independently. Levels of both can be high, both can be low, or one can be high while the other is low. Fish show distress when the O2 levels _in their tissues_ drop. If you have low O2 levels in the water, the presence or absense of CO2 makes no difference. The fish simply have no access to O2.

If water O2 levels are adequate (or even high), the fish can still show signs of oxygen starvation. Most commonly this is caused by high CO2 levels. High CO2 causes the blood to be less able to transport O2 effectively. The bottom line is there may be plenty of O2 around, but not enough is getting to the actual organs and tissues of the fish.

Secondly, the ph/KH/CO2 chart is pretty much worthless IME. The chart is only valid if CO2 is the only source of acid, carbonate is the only buffer, and you have an accurate way to measure CO2. Since these conditions are never true, the chart can never be accurate. A much better way to guage the actual CO2 level is to take a sample of aquarium water and run an airstone in it for several hours. Measure the pH of the sample, which is now at equilibrium with atmospheric CO2 levels. Aim for 1.0 or 1.1 pH units below this for your tank. This is reproducible, and IME has always been sufficient.

Finally, a KH of 260 is no big deal. My tank has a KH of 225 (by Lamotte) and I'm having no fish issues with a pH of 6.5. You might have issues with certain plants at this KH, but I'm keeping wild-caught rummynose tetras in this water with no issues.

At night, with the lights off, O2 is consumed by both fish and plants. If you have a tight lid, this can lead to issues, especially at higher temperatures. At high temps, the fish and plants consume O2 faster and O2 becomes less soluble in water. I'm guessing your fish load is pretty high too. All of this makes for a bad combination.

Regarding pH swings due to CO2 - don't worry about it. This type of pH change is 'transparent' and does not seem to affect the fish in any way. Running an airstone for a few hours at night will solve your fish respiration issues. Just turn the airstone off and start up your CO2 and hour or two before the lights come on to ensure that you get back up to a good CO2 concentration.


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