It may be that Brita has changed their system since I had one, or that they are different in the USA than the UK. You really need to do a few tests to see just how much the filter changes the pH if at all.
Run some tap water and test the pH immediately. Run some water through the Brita filter and test that immediately. If it's a jug filter, collect some freshly filtered water not water that's been standing in the jug.
Then run a glass of tap water and a glass of freshly filtered water, leave them to stand overnight and test the pH of both. You may well find that the tap water pH changes on standing. Comparing tap and filter water will show if the filter changes the pH - for example, if your tap water is pH 8, then the filter water at 7 is a lot lower.
Bottled water needs care. If it is pure water with nothing dissolved in it, you need to add minerals. If it does have minerals in, you need to use the same brand at every water change as different brands have different amounts of minerals.
Once the tank is cycled, tap water will be OK to use if you use a water conditioner which detoxifies ammonia for 24 hours. A cycled tank can remove that ammonia before it has chance to become toxic again. But you would need to chnage slowly from bottled water to tap water.
But you are doing a fish-in cycle so you don't have enough bacteria to remove the ammonia in the tap water.
1 ppm sounds quite high - does your water provider give a water quality report on its website? That should tell you if there is a maximum allowed level.
One other possible solution would be to keep some water in a container. Treat it with water conditioner to split the chloramine. Then have live plants in the container - anacharis or a floating plant. Plants take up ammonia as fertilser and can remove the ammonia from your tap water before you use it in the tank. But that would depend on whether having a large container of water with a light over it is possible for you.
Run some tap water and test the pH immediately. Run some water through the Brita filter and test that immediately. If it's a jug filter, collect some freshly filtered water not water that's been standing in the jug.
Then run a glass of tap water and a glass of freshly filtered water, leave them to stand overnight and test the pH of both. You may well find that the tap water pH changes on standing. Comparing tap and filter water will show if the filter changes the pH - for example, if your tap water is pH 8, then the filter water at 7 is a lot lower.
Bottled water needs care. If it is pure water with nothing dissolved in it, you need to add minerals. If it does have minerals in, you need to use the same brand at every water change as different brands have different amounts of minerals.
Once the tank is cycled, tap water will be OK to use if you use a water conditioner which detoxifies ammonia for 24 hours. A cycled tank can remove that ammonia before it has chance to become toxic again. But you would need to chnage slowly from bottled water to tap water.
But you are doing a fish-in cycle so you don't have enough bacteria to remove the ammonia in the tap water.
1 ppm sounds quite high - does your water provider give a water quality report on its website? That should tell you if there is a maximum allowed level.
One other possible solution would be to keep some water in a container. Treat it with water conditioner to split the chloramine. Then have live plants in the container - anacharis or a floating plant. Plants take up ammonia as fertilser and can remove the ammonia from your tap water before you use it in the tank. But that would depend on whether having a large container of water with a light over it is possible for you.
