For starters you need to ease up on the water changes. While you are trying to establish your tank, doing 50% changes so often is just restarting your tank. No one also asked this question. What type of water change are you doing? Gravel cleaning or just removing water. In your gravel is where the bacteria needs to start and if you keep stirring it up and removing all the waste you aren't letting it grow. Also, what type of cichlids do you have. you're ph seems too low to me. I keep mine around and have always had best results that way. The average established tank will see nitrates around 30 and ammonia at about .25-.5. Nitrites should always be at 0 but if you see a slight rise it's ok, just do a slight water change and check on your filtration. Also make sure you have adequate air flowing. I noticed you use an API test kit. The line on the villas are not actually correct. Use the cross section of the A for a more accurate amount. Or just use a medical dropper (use one that comes with your Childs medicine). Your temp is good with your feeding schedule, if you decide to increase food then your temp will need to rise to make them more active, around 78-79, once again this depends in what you have. You should have seen a spike by now which every new tank experiences, I think this is because of the constant water changes.
You are doing good but just let it be. Establishing a new tank doesn't happen overnight.
