25percent Water Changes Why This Amount ?

I got it off Ebay, which I know you aren't keen on. From this seller, though I see it's gone up 50p since January. There are lots of other sellers with similar, if not the same, splitter.
What to look for is a 2 way splitter as you don't need any more outlets than that, and ones with levers to control the air flow, not the kind that don't have them.


Just noticed a lot of sellers call them airline manifolds rather than airline splitters - the latter include the non-lever types.

check your water levels for ammonia and nitrite and pH. If all ok, unless there are any fish with obvious signs of distress, I'd monitor the tank for now and not make any more changes. If you still have the old food I'd go back to that just now. Keep the amount of changes you make to a minimum. The issue could be one of these changes or a combination of two or three.

Keep us posted, try not to panic 

EDIT: agree with Sue, water change won't hurt. It would help with the cloudiness.

I would, until you know the cause of the cloudiness.

It is possible that the airstone kicked up some mess off the bottom of the tank/in the substrate in which case it could have caused a bacterial bloom. Bloom bacteria are not the same kind as we grow in the filter, they live on organic matter and any mess on the bottom will contain fish poo and uneaten food which are organic = food for bloom bacteria. They live in the water column and multiply so fast we can see them as the cloudiness. Bloom bacteria don't harm the fish directly, like ammonia and nitrite do, but they can use up a lot of oxygen in the water. This can be a problem for most fish but not bettas. They evolved to live in oxygen depleted, stagnant water and they can get oxygen directly from the air. The good news is that once bloom bacteria have eaten all the organic matter in the water, they die and the bloom goes away.

Provided there is no ammonia or nitrite in the water the fish won't come to harm. But water changes will stop the cloudiness getting worse.