# Best pH for plants and fish?



## kcrossley (Feb 22, 2010)

For the last week I've been experimenting with my CO2 levels to determine the best pH for both my fish and plants. I was running my pH as low as 6.0, but my wife was concerned I was over stressing the fish, even though they weren't gasping for air. At that level I was able to keep most algae in check. 

Now, I'm running the pH at 6.4 but I'm having a lot of problems with hair, string and BBA. The only issue I had before modifying the pH (CO2) was hair algae. 

BTW, I'm also EI dosing ferts. I have a pH controller hooked up, but I'm not using it to control the regulator—yet. Instead, I have the CO2 on timer. It comes on 2 hours before my lights come on and stays on until 1 hour before my lights turn off. 

What am I doing wrong? What should my target pH be? Will having a stable pH level, which the controller provides help?


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## lauraleellbp (Feb 3, 2008)

pH changes from CO2 levels don't hurt fish. It's pH changes from fluctuating TDS (total dissolved solids) that can be problematic for them.

Get a drop checker with a calibrated 4dkH solution in it and set your pH wherever it needs to be to keep the drop checker green.

I'd dose some Excel to knock out the algae.

And you may need to lower your light/photoperiod if it's really taking over.


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## Darkblade48 (Jan 4, 2008)

pH is really not that important. If you can keep most algae in check at a pH of 6.0, then keep your CO2 that high to keep the algae in check.

Also, if you have a pH controller, why not hook the CO2 up to it?


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## kcrossley (Feb 22, 2010)

Darkblade48 said:


> pH is really not that important. If you can keep most algae in check at a pH of 6.0, then keep your CO2 that high to keep the algae in check.


6.0 seems kinda high, especially 24/7. What do you think?



Darkblade48 said:


> Also, if you have a pH controller, why not hook the CO2 up to it?


I wanted to make sure the probes had stabilized.


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## kcrossley (Feb 22, 2010)

lauraleellbp said:


> pH changes from CO2 levels don't hurt fish. It's pH changes from fluctuating TDS (total dissolved solids) that can be problematic for them.
> 
> Get a drop checker with a calibrated 4dkH solution in it and set your pH wherever it needs to be to keep the drop checker green.
> 
> ...


I have a drop checker. Green = algae. Green/Yellow = minimum algae. Please see my thread on Excel dosing: http://www.plantedtank.net/forums/algae/108445-excel-rcs.html


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## captain_bu (Oct 20, 2007)

I would set the pH controller based on your drop checker and plants' (and algae's) response to the CO2 levels. If the fish don't look stressed when your drop checker is yellow and pH is 6.0 and that level of CO2 helps to prevent algae then set the controller for a pH of 6. It can be tweaked incrementally later if you need to.

There is no need to run CO2 at night. Can't you use multiple timers so that the solenoid stays off at night and comes on an hour or two before lights on?

Agree that if you get your CO2 as high as it can go comfortably for the fish and you still have algae issues then you need to look into reducing your lighting.


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## kcrossley (Feb 22, 2010)

I was going to set it up like this:

Outlet --> pH Controller --> Controlled Outlet --> Timer --> CO2 Regulator

But, the owner of AquaticLife recommended against the timer, saying that the pH Controller would turn off the Regulator once the pH hits the set point.


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## kcrossley (Feb 22, 2010)

captain_bu said:


> Can't you use multiple timers so that the solenoid stays off at night and comes on an hour or two before lights on?


I do use multiple timers. The lights are only on from 2:00-9:00 pm (7 hours)


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## lauraleellbp (Feb 3, 2008)

I'd still leave it on a timer to shut off at night, and I'd also make sure you've got an airstone set up for nighttime too. Nothing like waking up to a tank full of dead fish... murphy's law.


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## Hoppy (Dec 24, 2005)

You can leave the CO2 on 24 hours a day if you have low enough light intensity that you don't need to run near maximum CO2 during the day. It also helps a lot if you make sure the tank water surface is always rippled, from filter return flow, or a powerhead, so the water has a maximum of O2 at all times, and CO2 loss from the water surface is high. But, if you want high light, one of the prices you pay for that is having to shut off the CO2 at night to keep the fish from suffering.


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## kcrossley (Feb 22, 2010)

Basically, I have 72 watts of light in a 29 gallon tank and I'm using a Hydor Flo for surface aeration. I'd prefer not to use an airstone at night as it seems to promote algae growth.


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## lauraleellbp (Feb 3, 2008)

kcrossley said:


> Basically, I have 72 watts of light in a 29 gallon tank and I'm using a Hydor Flo for surface aeration. I'd prefer not to use an airstone at night as it seems to promote algae growth.


That's a new one...

I doubt it's the airstone.


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## captain_bu (Oct 20, 2007)

lauraleellbp said:


> That's a new one...
> 
> I doubt it's the airstone.


x2....

It also sounds like you need to run your CO2 high enough to prevent hair algae problem that leaving it on all night would not be a good idea.


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## kcrossley (Feb 22, 2010)

Okay, I'll turn it off at night. What about the airstone?


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## Jeff5614 (Dec 29, 2005)

You're making things way too complicated. Stop concerning yourself with the pH. Use a dropchecker as a general indicator of your CO2. Use the fish, plants and algae as a better indicator. If your fish aren't hanging out around the surface or gasping at the surface, haven't lost their color, aren't acting listless and acting the same as usual then you don't have too much CO2 for them. There's no need to run it at night, the fish need a break from it and the plants don't use it. Maintain a good surface ripple. It increases oxygenation and allows the fish to tolerate more CO2. You can run an airstone if you want, but turning off the CO2 at night and having a good surface ripple and good flow throughout the tank should make it unnecessary.

If your CO2 is inadequate you're going to see algae and stunted plants. With good CO2, algae will gradually begin to disappear and plants will be healthy with no stunting as long as you're providing a nonlimiting supply of macro and micronutrients. You can gradually increase CO2 over a few days. If you see it starting to stress the fish then back down a bit. Work on circulation throughout the tank to get the CO2 well distributed. As long as you can see the leaves gently swaying in the current your flow is good.

Lower light makes all of this easier. If you still have algae issues, stunted plants, good flow and you can't increase CO2 without killing your fish then you need to lower the light.


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## Craigthor (Sep 9, 2007)

And most controllers won't turn on at night as after the lights go out the plants release CO2 instead of take it in. At that point teh PH should remain stable through the night and not turn on.

The more you mess with everything the more problems you will create. If your using a controller set it so the DC goes greenish/ yellow. Leave the controller on 24/7 and no need to use a time for the CO2 that is why you forked out big bucks for it why not use it for what it is for.

You spend too much time worrying and playing with settings, stop and jsut sit back and enjoy the tank for a change. On my tank I don't I don't test for anything, add ferts a few times a week, do a 50-90% water change once a week, feed the fish live foods twice a day, and spend atleast 2-3 hours a day watchign the tank and the the fish interact with each other.

Craig


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