Should we add a chiller

[stevenic]

My wife and I have just started up a new RSM 500 (135 gal) tank and are in the process of cycling it. We added an Apex controller to the tank so we could remotely monitor it and we live in the Pacific North West so we were hoping we could avoid having to add a chiller to the tank.

It's about as hot outside as it gets right now (80's to low 90's) and we're one of the rare ones that have A/C in our house. We currently have the tank set to maintain a temp of 78 and before the current heat wave started we'd see the tank temp rise to about 82 during the day with the lights on so about a 4 degree swing. I currently have the lights set to run 10 hours a day.

Before the current heat wave we were seeing a fairly steady sawtooth pattern where the tank would go from 78 to 82 during the day and then settle back down to 78 over the course of several hours during the night. Now that the heat wave has started we're seeing it take a lot longer to cool down and what happens is sometimes when the lights come on the tank hasn't completely cooled down so the Apex cuts the lights off after 6 hours or so. Adding further complications to things we have a Nest thermostat on our A/C which is kicking into "away" mode during the day so it thinks nobody is home and shuts the A/C off. I've tried changing the max allowed temp on the Nest for away mode but they won't let you set it below 76 for some stupid reason

The Apex is basically doing its job and when it shuts the lights off the tank temp stops rising. My questions are this... Is a daily temp swing of 4 degrees harmful to a reef tank and if that's ok is it ok to only have 6 hours of light some times during the rare hot days we have in the PNW? We don't have fish in the tank right now but I'd like to get this ironed out before I start adding them in another month.

Thanks in advance... -steve

[stevenic]

I should add that I'm not opposed to adding a chiller to the tank from a cost perspective. It's more that the RSM 500's cabinet is pretty tight. There's a spot for a chiller but I have dosing pumps I was hoping to put there. If we add a chiller there's not a great place for the dosing pumps and containers.

[scottwhitson]

I don't think a 4 degree swing is too much. I would attempt to use some fans blowing on the waters surface to help disipate the heat. Also if it has been running at an acceptable temp during normal weather you should be fine with a shortened light cycle for the odd days that the temps get so high. A lot of people do lights completely out for 5+ days at a time for algae control.

[stevenic]

Thanks Scott... On my drive home I actually had another thought. The RSM 500 has 10 tubes of T5 lighting which are broken out as 4+2+4. To save outlets on my Apex I combined all of these into one so they all come on and turn off at once. The thought I had was that if I break these back out to separate outlets I can turn the tubes on and off separately in increments of 2 to ramp the tank lighting up and down. This should better simulate the sun going up and down and help the tank to run cooler right?

Here's what I was thinking sequence wise:

2 tubes - 45 min
4 tubes - 45 min
6 tubes - 45 min
8 tubes - 45 min
10 tubes - 4 hours
8 tubes - 45 min
6 tubes - 45 min
4 tubes - 45 min
2 tubes + Moonlight - 45 mins
Moonlight - 6 hours

I'd need to use the Advanced mode of the Apex to program this but would still give 10 hours of lights while minimizing the full power output to 4 hours.

Thoughts?

[Reefer54]

have you tried just putting a fan over the tank or under, in the sump. i live in the rockies and have the same issue. i actually just posted what adding a 9 in fan has done in literally one day.

good luck

[stevenic]

Thanks Reefer... I don't want to run a fan externally because of the visual but inside the Sump is a good suggestion. May have to give that a try.

[Reefer54]

I generate a LOT of heat inside my stand. Even with one side open, and the door cracked, the air inside has to stay at least 5+ degrees warmer than the house, especially when the day lights go on over the sump at night. A fan has made a HUGE difference in there.

[stevenic]

Found this fan kit on amazon. I could suspend this above my sump and see if it helps.

[Reefer54]

I bought a 9 in round fan, that i screwed the base directly to the stand and ziptied the housing to keep the angle stable, basically across the length of the sump. Walmart. 16$ beats a chiller all day if it continues to suppress the heat.

[stevenic]

I just re-programmed my lights using the sequence I outlined above so want to see what impact that has on the temp curve first.

[Fallling]

I would suggest trying to add a fan or 2 first. Chillers need clearance in the front and back for proper air flow. I don't know if the cabinet is enclosed, but if it is, don't put the chiller in there. Even if it's not completely enclosed, I probably wouldn't put it in there. Typically, people put them next to the tank.

I have those small clip on fans by Air King (BRS sells them... got mine from Amazon), and they typically keep my tank at 80 - 81 even with 95 - 100 degree southern CA days and no central AC. Up until recently, the fans had kept the tank at 78 (until it really started warming up). Keep in mind the fans cause evaporation and hence much more top water will be needed.

With all of that said, I currently have a JBJ chiller that I haven't been running. If my tank starts running any warmer consistently, it'll be time to start running the chiller again. I'm almost at that point, but not quite yet. August and September are typically the warmest months for us.

Oh, and I should mention is 125 gal with 30 gal refugium plus sump.

[stevenic]

Falling, the RSM 500 tank I have has a dedicated compartment for a chiller that's well ventilated. The reason I didn't want to immediately add a chiller (other then the impact on the electric bill) is that I wanted to use that space for my dosing pumps and two-part containers. I saw the clip on fans on BRS last night and would certainly be my next step.

As it stands I mad the changes to ramp my lights up and down over a 3 hour period and as of now the tank is running 1 degree cooler then yesterday at the same time. I'm only half way through my light cycle but that seems to have helped. I'm currently only running the lights for 10 hours total so with the addition of the ramp up/down I may extend that to 12 hours total so I'm giving the tank 6 hours of full light versus 4 hours.

[ace_92101]

You could also bring the set temperature up a few degrees. But I agree on the fans.

[JoelA7]

Suggest not putting a chiller inside the cabinet. An accident resultng in cooked fish waitng to happen. They generate more heat outside them then the reduction of heat in the water.

[stevenic]

Thanks Joel... The light changes I made have dropped me down to about a 3.5 degree swing as of now (I extended the lighting cycle from 10 to 11 hours) and we're in the hottest part of the year for us. My next step would be to add a fan but not sure I even need that at this point, assuming a 3 - 4 degree daily temp swing is ok.

[sirreal63]

Originally Posted by stevenic

My questions are this... Is a daily temp swing of 4 degrees harmful to a reef tank and if that's ok is it ok to only have 6 hours of light some times during the rare hot days we have in the PNW? We don't have fish in the tank right now but I'd like to get this ironed out before I start adding them in another month.

Thanks in advance... -steve

Your temps are perfectly fine, no reason to get excited, many reefs are considerably hotter. Some good and informative reading here...

Originally Posted by MCsaxmaster

I'd humbly suggest that reading this series which I recently wrote for Reefs Magazine could be useful. It's a four part series entitled "The Great Temperature Debate":

http://www.reefsmagazine.com/forum/r...hris-jury.html

http://www.reefsmagazine.com/forum/r...e-part-ii.html

http://www.reefsmagazine.com/forum/r...-part-iii.html

http://www.reefsmagazine.com/forum/r...e-part-iv.html

The very short version is that most (i.e., not all, only most) coral reefs have historically experienced temperatures in the neighborhood of ~78-84 F and have spent relatively little time outside this range. Some reefs are hotter than typical and regularly spend time in the 84-87 F range (and even higher in the Persian gulf) and some reefs are cooler and regularly drop down to the upper 60's, or even lower. However, the extremes are poorly tolerated by most corals. Corals from all reefs can thrive at temperatures in the neighborhood of 77-82 F, and most are flexible enough that they can tolerate a few degrees higher or lower for a bit. You can see much more detailed discussion in the series.

Back to the original question: if it were my tank, I'd use a fan on it as suggested. I think a temp of 83 F is fine and pretty much all our critters will thrive at that temperature, but I wouldn't want to intentially let it get much higher. Some corals will tolerate many degrees warmer without problems, whereas those form cooler reefs won't. Putting a fan on should allow better temperature control.
cj