How often does your chiller turn on???

[Inland Reef]

How often does your chiller turn on in the middle of the day, with all lights on?

I'm wondering if mine turns on way too often. It's running probably 5-10x within an hour. I haven't logged it exactly.

I've always had T5's over my tanks, and have never had heat issues that required a chiller, so this is my first time running one.

I recently acquired a BC29 with a 150w HQI & chiller (Aqua Chill 1/10).

I've got the normal circulation pump in chamber 3, and the chiller pump (Rio 1200) in chamber2. The water return is on the right side, which is where the overflow is, but the return is mid way toward the front of the tank and blowing across the tank.

All fittings are tight, so it's getting the best circulation the Rio can put out. The flow rating on the Rio is 295gph, which the chiller owners manual states that it's adequate.

No other pumps in the tank.

Only running the 150w HQI and two LED stunner strips.

Room temp is 76-77deg

The chiller temp is set to 78deg.

The differential is set at +- 2deg.

I have a regular thermometer in the tank and the chiller temp seems to be pretty close to it. Maybe +1 degree or so.

This is also my first open top aquarium. It was putting off so much humidity into the room that it was raising the room temp by 2deg, so I had a glass top cut for it. The rear filter chamber is still open.

Even before I put the glass top on, it was turning on about as frequently.

When it does turn on, it cools the temp down within 2min or so.

So, does this sound somewhat normal? Is it turning on excessively?

Do I have it placed/setup incorrectly?

Any thoughts or suggestions would be great.

[Timfish]

I'm reading your post as your chiller is turning on and off or cycling between 5 and 10 times an hour. If this is so that strikes me as quite a bit. If I should have read it as running 5 - 10 minutes an hour that's probably still a little frequent but not necessarily so. The chillers I've worked with have had a 2 degree difference in set points also and typically will only cycle every couple of hours with T5s in a closed hood, this is partly a function of the size of the chiller to the tank. I've always tried to size a chiller to give a 20 degree pull down below ambient temp. on a given tank size. If your chiller is inside a closed cabinet make sure it's well ventilated or your chiller is working against itself.

[Inland Reef]

The chiller is turning on about ten times per hour. When it is on, it runs for about 2min while it's dropping the temperature from 80 to 78deg.

The tank is a BioCube29 that was an open top but I had glass cut to fit the top, so there is only 1/2" or so between the glass and water. On top of that sits the sunpod 150w MH.

The chiller itself is not within the cabinet; it sits beside it. It has the suggested 12" of space in front and behind. When it is running, it seems to be running efficiently as it only take a couple minutes to go from 80-78.

The ambient air temp in the room is 76-77, usually 77deg.

My thoughts are that maybe the pump isn't circulating the water through the chiller at the correct flow rate. The return water pressure doesn't feel very strong compared to the pressure coming out of the filter pump. Then again, it's got to push the water out of the tank, through the chiller, and back up to the tank.

Other possibility is that the thermometer inside the chiller is malfunctioning.

I'm going to hook up a dig thermometer and place it in chamber 2 along with the chiller pump to see if the water temp is really changing that quickly.

[Timfish]

Check the temp in the tank. If your flow is correct through the system the temp change in the biocube should reflect the temp change displayed on the chiller.

[Inland Reef]

Still not entirely sure the flow rate is correct, but a maxijet 1200 seems pretty common, so at this point, I'll assume that it is.

It may indeed be the chiller thermometer.

While doing a bit more research on the Oceanic chillers, I read several comments that the chiller thermometer could be off by as much as 2 deg from actual.

I dropped a digital thermometer in chamber 2 & sure enough, it was reading 77deg while the chiller was displaying 79. I got the same readings in chamber 1, as well as the actual tank. When I first got the dig thermometer I verified it with a regular mercury thermometer for a week, so I'm pretty confident thats it's accurate.

So, I thought I was keeping the tank at 78, but it was actually trying to keep it at 76.

I turned up the chiller temp to 80, which should try to keep the actual temperature at 78. All this happened after the MH was off, so it never got warm enough for it to turn back on. This morning at 10am the tank was at 78 (chiller reading 80), so we'll see what happens when I get home from work and the MH has been running for several hours.

This is making a whole lot more sense now. It was trying to keep the tank 1deg below room temp, with a MH over a closed glass top.

Hopefully turning up the setting on the chiller solves the problem. Don't know why I checked Everything else, before I verified that the chiller thermometer was accurate. That probably should have been the first thing I checked. Oh well.

Thanks for the responses Tim.

[DerrickH]

Should be a way to change the temp offset. Almost all chillers have these.

[mhart032]

5-10 times an hr is very very hard on the compressor. not to mention energy consumption

[Inland Reef]

Yes, the off set or differential is set: "The differential is set at +- 2deg."

This is the lowest setting on this particular chiller.

mhart032: I agree completely, thats why I was thinking something was not right. I don't have any experience, but that seemed excessive for a tanks temp to change that quickly.

I'll know later tonight if changing the temp worked or not.

[mhart032]

have you tried putting fans over the tank just to kinda help regulate the temp? i noticed when i put a fan over the sump that my chiller never kicks on. now my tank temps only swing about 3-4 degrees during the day. the chiller is grat for the backup incase the lights get stuck on or something like that. it may kick on every once in a while but ive never seen it.

Matt

[DerrickH]

differential is the degrees of rise before the chiller kicks back on. The offset if what your looking for. Basically a calibration setting to match ambient or a specified body of fluid. My chiller has this setting and I had to adjust it one degree. My tank runs one degree warmer than my sump. I dont have the chiller plumbed back into my tank, it feeds back into my sump. This makes the chiller run longer. I should drill another hole in my tank and plumb it into the MD but just can see myself draining water out, moving the tank/stand away from the wall and making a mess...

[Inland Reef]

Ahhh, thanks Derrick. That makes sense.

There is a setting marked pd, which comes after the differential setting. This isn't described in the owners manual so I wasn't sure what it was. It starts at 0 and goes up in single increments.

I'll see if doing a manual offset works. If not, then I may fiddle with the "pd" setting and try to figure out if that is in fact an offset.

Thanks for all the feedback. It's helped me narrow things down quite a bit.

I'll let ya'll know how things go when I get home and watch it for a couple hours tonight.

[DerrickH]

the pd is for the calibration of the temp sensor. its a +/- setting. This is what you need to adjust to fix the skew in monitored temp. If Im not mistaken, you need to raise it to +1 if your water is 1 degree cooler than what the LCD is displaying. You will just have to mess with it. When I got my first chiller, all the settings were reversed of what you would think they should be, almost like learning how to ride a bike backwards...

[Inland Reef]

Thanks Derrick, your feedback has been Very helpful.

Got a rare date night with the wife, so didn't get home until 10pm, then had to do some wfh. In between all that, it seems that I was still having the same issue of frequent chiller activation.

So, before I started fiddling with the settings, I was thinking, maybe the water output was on the side of the internal temp probe and thats why I was getting these weird readings.

When I say weird readings, I mean this: For example and simplicity sake; say the actual tank temp is 80. Chiller turns on, runs for a bit & then shuts off at 78. The actual tank temp is reading 79-79.5 So, the chiller is thinking it's cooler than the actual tank really is. I was thinking that maybe the water exiting the chiller is too close to the chiller thermometer, therefore skewing things.

So between working on servers, I decided to change the input/output hoses.

Side note: I was smart enough to know there was going to be a lot of water in the hoses, so I put the chiller on top of a bucket to catch whatever water flowed out of the hoses when I disconnected them. I disconnected the input hose first and water just gushed out of the chiller and didn't stop. I was like What tha Heck???. Turned off all power to the tank (filter pump) & it eventually stopped. Well, the chiller return hose was still sitting in the tank and basically created a vacume and started pulling tank water through it, similar to when you do a water change. Glad I had the bucket under the chiller, and a nice lesson to learn. Also facilitated my weekly water change that needed to be done anyways.

This was around midnight, so the tank temp was already down and the chiller didn't turn on again. On the positive side, The tank temp was reading 78 and the chiller temp was reading 79, so now there is only a 1 deg difference instead of two. So simply switching the imput/exit hoses had an immediate effect. Hopefully it solved the issue, but I'm still skeptical.

The owners manual shows 4 different diagrams for how the chiller can be setup and plumed out. 3 of the 4 diagrams show the input hose going int the right side port & exiting from the left port (if looking at it from the front), 1 diagram shows the opposite.

If that doesn't solve the issue, then my next step is to adjust the "pd" setting.

If that doesn't work then I'll most likely take it apart to see if anything is obviously wrong. Then take it in for service.

[DerrickH]

My chiller is set to one degree differential meaning it kicks off at 76f and does not come back on till it hits 77f. I do know the temp monitor on the heat exchanger in chillers is only on one port. It should not be monitoring on the output side as it only cares what the largest body of water temp is since thats the essential goal. Mines backwards but it kicks on for about 5 minutes every 2 hours or so. With mine being backwards, the tank runs about 1 degree warmer than whats in the sump. Im fine with that since it ends up being 77-78. I might change it this weekend to see if it reduces the rate of chiller cycles. Since you have started this topic Ive been thinking its time to tighten the spokes on this wheel.

Your going to have more cycles than me though since your lighting is "nuclear" compared to my 4 T5's on such a small tank.. I run a closed, non vented canopy so I get some heat but not like yours Im sure. Being such a small tank, the water temp will fluctuate a lot. Without the chiller how warm does it get? How long is your halide on?

[Inland Reef]

"Your going to have more cycles than me though since your lighting is "nuclear" compared to my 4 T5's on such a small tank.."

Nuclear is a very apt description. All my experience has been in PC, then upgrade as quick as I can to T5's. I'm seriously considering going back to T5's, but want to give the MH an honest shot. I just happened to give it a try in the hottest summer ever! My home AC has been working to keep the temp at 76. Timing is everything.

In the past, I've only been interested in softies, LPS, & clams, and all those were just fine under T5's. I got a great deal on this complete system, so figured I'd see what the deal was with MH's. So far, I'm not super impressed with the drawbacks of MH. Higher tank & entire room temp's, more electricity usage, requiring a chiller, etc. With my experience and seeing a few SPS tanks under T5's, I know I can get the same results. Although a full bank of replacement T5 bulbs aren't cheap compared to one MH bulb. There is always going to be some give and take.

LED's are looking very attractive, but we'll save the MH, T5, LED discussion for another thread.

I'll answer your question before I get into all the experimental I've been doing.

I'm running the MH from 12-7 right now. Not sure if that's ideal or not, but I'll work on that after I figure out the chiller.

I'm not sure what the tank temp would end up at if I didn't have the chiller running. It would be above 82, so I didn't want to find out exactly how high it would go.

After doing a lot more reading, I'm starting to think that the problem is low flow through the chiller.

It's keeping the tank at the desired temp, but it's cycling on/off a lot to keep it there.

I've been monitoring the tank temp and while the chiller is not engaged, it has an accurate temp reading (figuring in the 1deg offset).When the chiller is engaged, the outflow is cooler, but doesn't get a great deal cooler before the chiller shuts off. The outflow is very weak; at least 1/2 that of the filter pump which is rated at 295gph. I think with the under powered flow, the chiller water chamber is cooling down too fast, and therefore tripping the temp & shutting it down. With increased flow, it should keep the chamber closer to tank temp, therefore providing an accurate reading.

I'm using a maxi jet 1200 which is rated at 294gph. 3ft vertical from chiller to the top of the tank, & 1.5ft horizontal. There is one 45 angle & 3 90deg bends from pump to return outlet. In a product review done by Advanced Aquarists they found that the actual flow with 4ft head was 155gph. So figuring in my vertical, horizontal, & restrictions, I'm probably a little shy of 150gph. I used the RC head calculator, but don't think I used it correctly as it said I would have 0gph flow.

The chiller manual states that it needs 20-300gph.

The maxi 1200 seems to be a rather common, albeit "budget" choice. Hopefully I'll be able to make it work.

I've already cleaned in thoroughly, & it's throwing out some high flow when not hooked up to the chiller.

I'm going to try using some eheim soft U curve's to eliminate the 3 90deg & 45deg elbows. I'll also eliminate as much wasted tubing as I can. Hopefully those changes will get the flow rate up to 200+ & solve my problem.

Keeping fingers crossed....

[Bry]

I know you want to figure out the chiller, but I just want to 2nd want mhart said above about a fan. My tank runs 80-82 in the summer. I didn't like that although my tank seemed fine. I added a small clip on fan and just pointed it above the tank, not even into the water and WOW, got down to 76 before I turned it off. I now have it down above the sump so I can stay closer to the 79-80 range. Again, off topic but worth the $$ savings.

[Inland Reef]

I agree completely. A simple fan can make a night and day difference in tank temp!

I've got an oscillating fan circulating the room air, but I've been considering a small clip on desktop fan to blow across the glass. This would help to reduce the heat transferred from the MH light to the glass top, & in turn to the water.

To the main topic. I think I am on the right track with the flow issue. By replacing 3 of the 90deg elbows (on the return) with the eheim soft curve 180, the flow was dramatically increased.

Now the chiller is turning on once an hour. It's still not optimal as the chiller temp (while running) is slightly skewed & shuts off just shy of the desired tank temp. I plan on adding the other eheim soft curve to the pump side, & I'll be able to eliminate close to 2+ ft of unnecessary tubing, which will reduce the head pressure.

So hopefully I'll have this problem solved pretty soon.