Ok, first what are your readings? PH, ammonia, nitrite and nitrate. What filter are you using. What stock do you have etc. Need more info on the setup before anyone can really help.
The ph is 8.4 was always 7.6 everything else is fine. have 15 cichlids and have added live plants. filter is marineland 15 gallon undertank with 3 trays 2 have blue filtet pads the bottom has 2 bags of carbon. sorry dont know much about it got it used from a friend
You need to get a liquid testing kit to test for Ammonia, Nitrite and Nitrate.
By providing actual numbers for these readings we can better help you.
The chances are that you are experiencing a bacteria bloom which is common in new tanks. However the bad news is that this means your tank is not cycled and as such your fish maybe at risk of Ammonia/Nitrite poisoning.
If you could get some actual numbers for the above mentioned elements we can give you more help.
API FRESHWATER MASTER TESTING KIT is what most freshwater aquarists here on AA use.