Fish Rooms - increased HVAC or chillers?

[WhatCouldGoWrong71]

Post that started this:
https://www.reef2reef.com/threads/need-advice-mixing-salt-with-cold-rodi.1091205/#post-13204391
I have a build thread but my Insta has more:
https://www.instagram.com/thedryreef?igsh=MW1wZmxkOWptdWVhcw==&utm_source=qr
So I’ve been struggling with temps in both my fish room and my system.

My fish room has a whole house dehumidifier and a 12k BTU portable AC. I closed off all vents to the fish room from my house’s HVAC unit. I don’t want to have humidity issues between my FR and my house. I also built a room within a room, I used 2/3rds of my formal dining room for this build (we’ve never used the space). I had a contractor build plywood walls and run another 125amp service to this room solely for this tank. Panel box is outside but on the same wall. I also have 3 windows in the room. I used a bunch of lights (8 XR30s, T5s and 6 halides). The portable AC works great, but, the thermostat is built into the unit. So, during the winter the exhaust hos gets cold from the outside plus heat rises and cold air sinks. So, at 40 inches off the ground my room. Could be 15 degrees cooler than at 7 foot. I shut my halides off at 80.5 and Radions at 81, I keep the tank at 77. Very very often I am bumping up against the 80.5, so I see those swings daily. I’m still acclimating my system to my lighting, I’m at 4.5 hours of the planned 6.5-7 hour daily schedule. However, I rarely make it to 4 hours. Lately, the temps outside have been 20 degrees, so opening the window with a small fan can get the room chilly which in turn keeps the system in check.

I purchased a 12k btu mini split ac/heat. When it warms up I plan to install it.

2 questions:
1) Will a ac really help keep my display temps in check? I’m new to a fish room. I keep my house at 70, so the fish room is like to keep around 74. I’d like to hover around 77 degrees for the tank.
2) Can you run an AC when it is 28 degrees outside?


As for the temp swings, I’ve never had coral with such explosive growth and PE. With crazy high par and lots of flow, they are loving it. So if there is more to go with further stability, I’m looking forward to it.

 

[Daz_1978]

For clarification:
After the lights have been on for 4 hours, the temperature in the bottom half of the room can be 74°F and the upper half can be as high as 89°F? Is that the 15° difference you're explaining?

I'd recommend exhaust fans in the ceiling. They can be placed on thermostat control. That will pull the heat out versus trying to re-cool it.

Are you sure the portable AC has no remote thermostat option or kit that you could purchase?

The sad news is that a split system of any kind is typically designed to only cool when the outside temperature is 60°F or higher. You'd likely kill a mini-split pretty quickly in 28°F weather.

Not a solution, but might help with more stable water temperatures: An aquarium chiller.
Or... You could even make a more homemade version of a chiller if the lower room temperature is maintaining low 70°F's. Let the return-to-sump water run through LONG tubing to cool down closer to the lower room temperature (think the opposite of geothermal heating). Or some other genius idea to give the water more contact and longer contact with the lower room temperatures.

A 3-4°F water temperature swing in a day isn't huge... Do you know how high it will get if you ran the full light cycle you want?

 

[WhatCouldGoWrong71]

For clarification:
After the lights have been on for 4 hours, the temperature in the bottom half of the room can be 74°F and the upper half can be as high as 89°F? Is that the 15° difference you're explaining?

I'd recommend exhaust fans in the ceiling. They can be placed on thermostat control. That will pull the heat out versus trying to re-cool it.

Are you sure the portable AC has no remote thermostat option or kit that you could purchase?

The sad news is that a split system of any kind is typically designed to only cool when the outside temperature is 60°F or higher. You'd likely kill a mini-split pretty quickly in 28°F weather.

Not a solution, but might help with more stable water temperatures: An aquarium chiller.
Or... You could even make a more homemade version of a chiller if the lower room temperature is maintaining low 70°F's. Let the return-to-sump water run through LONG tubing to cool down closer to the lower room temperature (think the opposite of geothermal heating). Or some other genius idea to give the water more contact and longer contact with the lower room temperatures.

A 3-4°F water temperature swing in a day isn't huge... Do you know how high it will get if you ran the full light cycle you want?

You confirmed my fears as did Google. I need the mini split regardless but, I’ll need to manage this differently. I’m upping my fan game. I ordered two 12” commercial fans that push a tremendously increased amount of air then compared to what I have in play now. I am also adding 2 - 4” AC infinity inline duct fans. I will pull air from above the light rack out of the room and exhaust it outside while using the other one to replace the air with outside air. I am thinking the thermostats on the units combined with this time of year might be able to help regulate the temps in the room to get to a better consistency for the display tank. The portable AC doesn’t have an option, but, I will repurpose this in my wet room in the garage. The heat in my mixing station can be so bad that I have a 1/2 HP chiller on my mixing station. I recalculated and my system is currently about 520g (est). I’m going to do a different frag tank, so I think I end up about 700g on this system. I also have Halides on my Frag tank. I’m not a fan of running a chiller outside my house. I’d have to draw and explain why. Bottom line, my fear is some neighborhood kid could get mischievous and break the line. If I did a chiller I’d want to fabricate something to exhaust the heat outside one of the 2 windows I can get to. And no, I do not know how high the temps would get. Opening the window with a fan in it has been working, to a point. But I had a near miss with this method too, you can hear a bit about that here:

 

[Daz_1978]

In the short term, you could get a window fan and put it on a thermostat. Blow some of the cold air in the room when the temperature gets over a certain temperature.

 

[WhatCouldGoWrong71]

In the short term, you could get a window fan and put it on a thermostat. Blow some of the cold air in the room when the temperature gets over a certain temperature.

Hmmmm. I wonder if they make household window fans with louvers. You’re right. Connect this to my apex. I already have a probe I use to measure the room temp so I can watch temps through my apex for ambient air temps. When the fan is off louvers shut. Hmmm

 

[Blue Ring Octopus]

Watch this video on EG4