I wanted to share my experience with Recovery Ventilators as they don’t seem to get a lot of attention in the Reef Hobby. I’ve seen mention of them in a few threads/videos from Adam of Battlecorals and Than of Tidal Gardens, but not much beyond that.
They come in two flavors: Heat Recovery Ventilators (HRVs) and Energy Recovery Ventilators (ERVs). Both are used to bring in fresh outside air while expelling stale inside air. The have a core where the two air streams cross over each other, exchanging heat in an attempt to bring the outside air temperature as close as possible to the inside air temperature. The intent is that you recover the energy that was used to heat or cool the inside air, hence “recovery ventilator”. HRVs exchange heat, while ERVs exchange both heat and moisture.
I have three reef systems totaling about 1500 gallons, with almost all of the tanks located in my basement. I use evaporative cooling, so keeping humidity down is always a challenge. If humidity gets too high, my tanks will heat up until the threshold is reached where I have my Apex shut off the lights.
I’ve installed inline air intake and exhaust fans to exchange inside air with outside air as one means of controlling inside air temps and CO2 levels. During Spring and Fall when there are days of rain, higher temps, and humidity near 100% I cannot bring in outside air as it’s too warm and humid to permit evaporative cooling. During these periods I’ve observed high CO2 levels, lowered pH levels in the tanks, and less stability with alkalinity. I believe I’ve also experienced a negative impact to coral health as a result. I suspect high CO2 resulting in low pH and less alkalinity stability could be one of the reasons people experience seasonal losses.
I already use oversized skimmers with fresh air intakes. I’ve tried CO2 scrubbers, but the media exhausts very quickly. I’ve also used kalk in the past, and while I know a lot of people have success with kalk, I find kalk reactors prone to clogging and other issues. I’ve even used lye instead of sodium carbonate as the alkalinity portion of two-part, but that comes with handling and impurity concerns.
A few months ago I pulled the trigger and installed a RenewAire EV Premium L ERV. It has Electrically Commutated (EC) motors, so it runs very efficiently at lower speeds. It also has a boost function where you can close a circuit to have it run on demand at 100% speed. I control its power and boost circuit via Apex outlets based on CO2 levels. I’m monitoring CO2 via the Apex as well. I have it turn on to a low speed whenever CO2 is above 600 ppm, and boost mode (max speed) when it’s above 700 ppm.
Since installing the ERV my pH is higher, extremely stable, and my alkalinity is rock solid as a result. It’s one of the best investments I’ve made for the reef tanks, so I wanted to take some time to share my experience.
Here’s a plot of pH in one of my systems and the CO2 level in my basement prior to installing the ERV. This was during winter so I can bring in fresh air while the lights are on, but it’s too cold to bring in fresh air during the night. During the aforementioned high humidity periods my CO2 levels would get much worse than this, sometimes approaching 2000 ppm when it would rain for several days on end.
Here’s a plot after the ERV was installed. My average pH has increased by 0.15.
A few pics of the ERV installed:
They come in two flavors: Heat Recovery Ventilators (HRVs) and Energy Recovery Ventilators (ERVs). Both are used to bring in fresh outside air while expelling stale inside air. The have a core where the two air streams cross over each other, exchanging heat in an attempt to bring the outside air temperature as close as possible to the inside air temperature. The intent is that you recover the energy that was used to heat or cool the inside air, hence “recovery ventilator”. HRVs exchange heat, while ERVs exchange both heat and moisture.
I have three reef systems totaling about 1500 gallons, with almost all of the tanks located in my basement. I use evaporative cooling, so keeping humidity down is always a challenge. If humidity gets too high, my tanks will heat up until the threshold is reached where I have my Apex shut off the lights.
I’ve installed inline air intake and exhaust fans to exchange inside air with outside air as one means of controlling inside air temps and CO2 levels. During Spring and Fall when there are days of rain, higher temps, and humidity near 100% I cannot bring in outside air as it’s too warm and humid to permit evaporative cooling. During these periods I’ve observed high CO2 levels, lowered pH levels in the tanks, and less stability with alkalinity. I believe I’ve also experienced a negative impact to coral health as a result. I suspect high CO2 resulting in low pH and less alkalinity stability could be one of the reasons people experience seasonal losses.
I already use oversized skimmers with fresh air intakes. I’ve tried CO2 scrubbers, but the media exhausts very quickly. I’ve also used kalk in the past, and while I know a lot of people have success with kalk, I find kalk reactors prone to clogging and other issues. I’ve even used lye instead of sodium carbonate as the alkalinity portion of two-part, but that comes with handling and impurity concerns.
A few months ago I pulled the trigger and installed a RenewAire EV Premium L ERV. It has Electrically Commutated (EC) motors, so it runs very efficiently at lower speeds. It also has a boost function where you can close a circuit to have it run on demand at 100% speed. I control its power and boost circuit via Apex outlets based on CO2 levels. I’m monitoring CO2 via the Apex as well. I have it turn on to a low speed whenever CO2 is above 600 ppm, and boost mode (max speed) when it’s above 700 ppm.
Since installing the ERV my pH is higher, extremely stable, and my alkalinity is rock solid as a result. It’s one of the best investments I’ve made for the reef tanks, so I wanted to take some time to share my experience.
Here’s a plot of pH in one of my systems and the CO2 level in my basement prior to installing the ERV. This was during winter so I can bring in fresh air while the lights are on, but it’s too cold to bring in fresh air during the night. During the aforementioned high humidity periods my CO2 levels would get much worse than this, sometimes approaching 2000 ppm when it would rain for several days on end.
Here’s a plot after the ERV was installed. My average pH has increased by 0.15.
A few pics of the ERV installed:
