ph swings up at night

[Paul Minett]

guys need some advice, think I have found a cause for a few unexplained deaths recently, done 2 ph tests before the lights came on ph 7.5 rechecked twice the other was an hour later with lights on ph 6.5 , the tank is heavily planted and no CO2 so would expect it to swing the other way if anything, so any advice on cause and cure would be greatly appreciated.

lights on normal paramaters Ph6.5, KH 1, GH 4, NO2 0, NO3 5, ammonia 0,

[jayc]

Weird.

You'd think pH would drop at night as CO2 levels increased.

It would rule out CO2 issues if that's the case.

Something else is increasing your pH.

What substrate and filter media are you using?

Do you have rocks for hardscape? If so, What sort of rocks?

Best to take a sample of each and test in a cup with Distilled or Demineralised water.

See if you can find the culprit that is raising pH.

[fishmosy]

I'd suggest redoing the tests. Maybe there was some contaminant in the first test (lights off) e.g. Some left over powder in the test tube from another test. Like jayC said pH should only drop at night and its not usually anything like 1.0pH.

[Paul Minett]

re did the first test 3 times in 2 different tubes same result, no rocks in tank benibachi soil some driftwood and lots of plants, filter has noodles carbon and purigen, as you have said the ph should drop not rise this much hence why I am stumped and looking for answers

[Wraithie]

What sort of noodles do you have and how old is your carbon?

[ninja]

To rule out one potential problem, get a new kit. I change mine every year or less!

[jayc]

Carbon!

All carbon media contain ash that can and will raise pH, especially newly added carbon. Was carbon added recently or is this a new tank?

Activated carbon contains ash as a residue of the carbonization and activation process. These inorganic leftovers, mostly iron and calcium oxide, can be removed by soaking the carbon in distilled or R/O water before placing it into the aquarium. Ash reduces the activity of the carbon and will increase the pH level over time.

Is there a specific reason you are using carbon?

There should be no reason for using carbon as a long term filter media, unless you are trying to absorb excess medication or chemical compounds.

You don't state how much carbon you are using and the size of your tank.

Too much carbon for the tank size can significantly alter your pH.

3 tablespoons of carbon is enough to service a 190 liter tank.

How much carbon have you added?

The brand of carbon can also raise pH in varying levels. Cheap activated carbon media has been known to raise pH significantly.

Not to mention Carbon filters and media also contain Phosphates, leading to excessive growth of algae.

I would definitely run a test with some of that carbon in a cup of water as a test. Check pH prior to adding the media, then check pH a few hours after adding the media.

Check the noodles as well.

Cheap noodles have been known to alter KH and thus pH.

But your KH is low, so this is unlikely.

The combination of your Benibachi soil and carbon is giving you the fluctuating pH results.

The soil is trying to buffer pH down while the carbon is increasing it.

[Paul Minett]

that's very interesting was unaware of carbon doing that I have always used it in filters as a precautionary measure. will remove it and monitor thanks this seems to make some sense will give an update in a day or two when I have a result. thanks guys

[Paul Minett]

ok guys thanks for all your help yesterday took out the carbon did a water change this morning it still moved a little but only .2 will monitor over the next few days hopefully it will settle down more. wo0uld never have guessed carbon would effect it like that.

[jayc]

Do you mean it moved 0.2 from 6.5 to 6.7? Instead of the usual 6.5 to 7.5 ?

Just for the records and for others who might encounter a similar issue, can you give us some details of the carbon?

how long ago was it added?

How much?

Tank size?

Brand?

[Paul Minett]

today it only moved from 6.7 to 6.5, it was activated carbon aqua one chemi carb in the overhead filter like I have always used in other tanks. the shrimp tank is a aqua one 620 90 litre the carbon was replaced about 2 months ago about 1/4 of a cup worth. will check again tomorrow to see if it was the carbon or if the water change effected it.