Lowering Nitrate in Fish Tank

[Anonymous]

I have a 29 gal freshwater tank that I established in October. Added fish slowly and now I have 4 tiger barbs, 3 danios, 3 tin foil barbs, 2 painted fish, 2 small aquatic frogs, 3 nerte snails and three live plants. All of the fish are small. All chemical levels were good until a couple of weeks ago when my pH crashed unexpectedly and I lost 2 painted fish (used to have 4). Since then, levels just won't get back to normal. I have increased frequency of water changes (20-25% at a time, once a week for three weeks) and my pH stays at 8.0 (even using Neutral Regulator, my nitrite stays at zero, ammonia at 0.25 and nitrate at 40-80 (hard to tell the difference in color using the liquid tester). Of note, I tested my tap water and it's nitrate was 5.0.

Am I harming my fish? Are there too many? Should I increase water changes or is this my new normal? I have decreased feeding to once a day and only a pinch (not enough to cover the top of the aquarium). The tiger barbs act like they are starving. They eat quickly before others seem to get to the food and frequently chomp on the plants.

TIA for the advice.

Signed,
still loving my new hobby

[Anonymous]

I don't think you have too many fish. Are you feeding the plants? Is there dead plant debris? Try changing 40% of the water. I would be more worried about the pH. What's the pH of your tap? Have you tried to pull it down. The buffer won't decrease it very well. It just helps it from making drastic changes.

[Anonymous]

OP here. I haven't tested the pH of my tap water but will do so. Removed a dying plant last week but I've done two 20% water changes since then. I am not feeding the plants (should I be?)

[Anonymous]

Are you using carbon in your filter? You can experience spikes in the tank if you remove too much water during water changes. Try to limit the change to just 10%.