Ph ?

[Italian_Stallion]

the ph out of my tap water is 7.5 but when i do a water change and then i check the water the next day my tank water is around 5.5
the ph in the tank water used to stay around 7.5 but recently its started to drop. the tank is a planted 3ft and it has 3 bn plecos and 6 baby angelfish.
how can i stabilise the ph ?

thanks

 

[annka5]

To see if the issue is with the tank or with the tap-water, then fill a cup with water in the evening, and test the pH. Leave the water overnight, then test the pH again in the morning. If it has fallen (I think due to gases) then by storing the new tap water for a few hours before using it to do a water change will allow the pH to stabalize before it affects your tank.
It could be that the water company has changed additives to the water. Am really not sure of chemistry though!
Alternatively, the problem miught be that the tank is too dirty - the pH will drop as things decompose and nitrate is produced. Has your water change schedule changed/ overfeeding? Sounds rude, don't mean it to.
Am assuming you're not adding CO2 to the tank or anyhting like that - this will also affect water chemistry.

 

[modernhamlet]

One possibility is that your KH is really low. Do you have a KH test kit?

 

[rdd1952]

As modernhamlet said, it definitely sounds as if you have no beffuering capacity. How much water are you changing at a time? If you're only changing 10 to 15 percent, then you wouldn't see a big rise in the pH after a water change. For example, if you change 10%, you should only see a 10% rise in the tank pH from 5.5 to 5.7 which are both lower than my kit shows (6.0 is lowest reading).

There is an upside to the low pH though (depending on the fish you have). Ammonia becomes non-toxic at pH levels of about 6.0 or lower. If your fish appear happy and healthy, then you probably don't have anything to worry about. And on top of that, you could keep discus or even true altum angels since the love a low pH.

 

[Tokis-Phoenix]

Another thing that could affect ph...does the tank have any bogwood, sandstone/limestoen based rocks or coral sand? Although these things either cause the ph to rise or lower they can make it fluctuate in general. I would personally advoid from using any ph altering chemicals as these cause much stress to the fish.
How long has the tank been set up?

 

[Italian_Stallion]

thanks for the replies.

yes the tank has 2 large pieces of bogwood in there. the tank has been set up for about 6-8 months. i change the water once a week and do about a 20% water change and i gravel vac when i do a water change.
KH is carbonate hardness right ? i do have a KH test kit but i have neva tested it i'll test it now then.

also, would a low ph be bad for most fish ? i no some species like the low ph but was just wondering if will harm some fish in the long run ?

and no im not addind CO2

thanks