Question - PH Problem

[kill4u]

Hello,

Does anyone have an idea what could be causing the ph to drop in my Fish Only 55 gallon aquarium??.... 2 Tomato Clowns and a Niger Trigger along with 2 snails.....

I do not see anything that sticks out in the water parameters...

temp: 77.8 degrees
ph: 7.4
Salinity: 1.021
Ammonia: 0 mg/L
Nitrite: 0 mg/L
Nitrate: 40 mg/L
Calcium: 340 mg/L
Phosphate: 0 mg/L
Alkalinity: 9 dKH

After large water changes the ph will rise to close to about 8.2 before falling about 7 days later......

I am using RO/DI water on both of my tanks..... The 90gal tank seems to always maintain a ph of approx. 8.4.....

I have begun leaving the lid open to try to increase the amount of Oxygen that enters the water....

Does anyone have any ideas????

Thanks,
Brian
(aka Kill4u)

 

[mr_fosi]

Hello,
After large water changes the ph will rise to close to about 8.2 before falling about 7 days later......

Could be a high amount of heterotrophic activity (lots of CO2) or the 40 mg/L NO3 dragging it down. How often, how much and what foods do you feed?

The 90gal tank seems to always maintain a ph of approx. 8.4...

How is this tank stocked and fed?

I have begun leaving the lid open to try to increase the amount of Oxygen that enters the water....

If it is a gas exchange problem (which I suspect it is) you don't need more O2 in the water, you need less CO2. There are several things you can try:
- Keep your lid open and increase surface agitation.
- Blow air across the top of the water with a fan.
- Use an air pump and diffuser.

You can try all of these at the same time if you like to achieve maximum effect. If/when you try one of these, give it a few hours to work before you check your pH again.

Generally speaking, agitation and aeration do a great job of driving off excess dissolved gases and re-equilibrating tank water. However, I have seen cases in the past where the air in a person's house was just higher in CO2 than average. In those cases, the person needed to increase ventilation to the room were their tank was.

Give one or more of the above suggestions a try and see how it looks after a few hours.

 

[bastanford]

the best way to displace the CO2 is through the use of a protein skimmer. a high efficiency protein skimmer will introduce a tremendous amount of O2 into your system. I use two on my 45gal. also, they are great at cleaning the water. you won't believe the muck and crud that is in your "crystal clear water" until you see what a good protein skimmer will pull out. and, by getting rid of the waste before it breaks down, you will cut down on your nitrate production as well.

 

[kill4u]

I will give these a try......

I expect that the CO2 is the problem....

I will try to add an air pump and diffuser... Keep the lid open.....

I have a protein skimmer that is not currently hooked up..... I will try to add the skimmer within the next couple of weeks......

Thanks for the guidance......

 

[wade1]

and, by getting rid of the waste before it breaks down, you will cut down on your nitrate production as well.

Bonus points for the most proper answer to a skimming related topic I have seen on a forum in a long time!

Activated carbon can also play a role in removing the organics from the water column prior to them breaking down into nitrogenous (and other) wastes.... I would highly recommend the skimmer be brought online first.

 

[mr_fosi]

Curious about whether any measures were taken and what the results were.

 

[kill4u]

I kept the lid open and added an air diffuser and pump..... Seemed to help.....

I am currently waiting for a part for my protein skimmer before I give it a try.....

Thanks for all your help...
Brian