[Heckler70]

I use an ERV and yes it helps. My house stays around 850ppm co2. During cooking(gas) co2 shoots up to 1500-1800 and stays there for some time unless vented. I think even with running the skimmer outside, the tanks surface exchange/sump is enough to override the fresh air skimmer when the C02 levels are high. My tank was consistently
at 7.6 to 7.7 before ERV and fresh air to skimmer. Now I get 7.78 to 8.0 depending on amount of fresh air in house. ERV only 7.9. Windows open all day 8.0