Really big water temp changes

[Arcrgirl]

New to saltwater tanks, after having freshwater for a few years I decided to try my hand at salt when my little brother got rid of his tank and gave it to me. It's been cycling with no fish, just cc and a couple live rocks for the last two months while I worked on trying to familiarize myself with the process and do as much research as I can when I have time before adding more to it. It's a small 20 gallon (fish tanks in tiny apartments is difficult) with an over the back filter, two heaters and an air pump. After testing the water the last few days and getting consistent neutral results, i decided to add a common clownfish to get it cycled through the rest of the way. I got home, put the bag in the tank to acclimate the temp and 20 minutes later when I checked it, the water temp had dropped drastically. 78 down to 65. I took the bag out and put it in my soup pot on the counter and slowly added lukewarm water to warm the poor fish up again while I tried to figure out what happened. The tank warmed up again and I tested both heaters separately to make sure they work and they do, I tested the water again to make sure it didn't have a negative effect and the salinity which had been stable at 1.022 was up to 1.028.
This isn't normal right? Is it possible that the lighting helps heat the water that much so by putting the bag in the water to acclimate it blocked the lights too much? Any ideas? I don't want to put this little guy in the tank if it's going to keep fluctuating that drastically with the gravity so high.

 

[Daddy-o]

Not normal, lights shouldnt affect temp too much otherwise tank would freeze at night. How many watts are your heaters?
Cheers! Mark

 

[Quietman]

Small tanks do fluctuate more as you'd expect. Seems a bit drastic on heat and salinity on your tank though.

Salinity can be measurements - What device you using - hydrometer or refractometer. The former can be a bit inaccurate but should be consistent...the second needs calibration. What kind of water are you using top off for evaporation? If using saltwater, that might explain the salinity.

For heaters I doubt the bag is dropping temperature than much either through blocking light or a temp difference. Heater controllers are notoriously fickle but if you checked them since and you have 2 hard to say, if they're smaller it could take a while to compensate if your house is colder.

It's pretty much a universal recommendation to get a heater controller - even if cheap - I use inkbird but have used black box generic on freshwater...both are good, cheap and significantly better than internal inexpensive heaters. Higher end heaters have better controllers.

 

[Arcrgirl]

Not normal, lights shouldnt affect temp too much otherwise tank would freeze at night. How many watts are your heaters?
Cheers! Mark

They're both 100 watt. It stabilized some after I turned them off (one at a time) and waited 15 minutes before turning them on again. The temp is still fluctuating within a 6 degree range pretty often but I added the clown and he seems to be doing great and is really active.

 

[Lizbeli]

If your temperature is fluctuating 6 degrees I would be concerned. How old are these heaters? If they came with your brothers tank and have some age to them, it wouldn’t hurt to replace them.

+1 on getting an external temp controller. I also use an Inkbird with good results. If you decide to buy one of these I would recommend getting the model with the black coated probe.

Side note.. your salinity at 1.022 was a bit low before you got that spike. Try to aim for 1.025/1.026.

 

[Arcrgirl]

Small tanks do fluctuate more as you'd expect. Seems a bit drastic on heat and salinity on your tank though.

Salinity can be measurements - What device you using - hydrometer or refractometer. The former can be a bit inaccurate but should be consistent...the second needs calibration. What kind of water are you using top off for evaporation? If using saltwater, that might explain the salinity.

For heaters I doubt the bag is dropping temperature than much either through blocking light or a temp difference. Heater controllers are notoriously fickle but if you checked them since and you have 2 hard to say, if they're smaller it could take a while to compensate if your house is colder.

It's pretty much a universal recommendation to get a heater controller - even if cheap - I use inkbird but have used black box generic on freshwater...both are good, cheap and significantly better than internal inexpensive heaters. Higher end heaters have better controllers.

Hydrometer for now, so that could explain the shift. To top off I use distilled tap water and mix in Seachem marine conditioner to remove the chlorine then add it in and test the water a half hour later to make sure I don't need to add anything. I thought maybe the salinity could have read so high because the water was still below 76°, salt is more concentrated in colder temperatures but I couldn't be sure on that since I don't have a refractometer. Both heaters are Marineland suited for 15-30gallons.
I'll look into your reccomendations for sure, I don't want to try and do much else to my tank with the temp being so sporadic.
So far today it's been fluctuating between 82 and 76, have the heaters set on 79. It still seems like a pretty big swing though. But my clown is really active and seems to be doing well.
Thanks for your reply!

 

[Arcrgirl]

If your temperature is fluctuating 6 degrees I would be concerned. How old are these heaters? If they came with your brothers tank and have some age to them, it wouldn’t hurt to replace them.

+1 on getting an external temp controller. I also use an Inkbird with good results. If you decide to buy one of these I would recommend getting the model with the black coated probe.

Side note.. your salinity at 1.022 was a bit low before you got that spike. Try to aim for 1.025/1.026.

I bought both heaters brand new as his were a few years old. The salinity today measured at 1.024, but it's good to know that it should be a little higher, I'll aim for that in the future! On my next pay day I'll check out the temp controller you suggested!

 

[WVNed]

A 20 gallon tank has quite a bit of thermal mass and would take quite a while to change 6 degrees up or down.
How are you measuring the temperature. Does it use a probe that can be in and out of the water.
If a tiny bag of water was cold enough to lower the 20 gallon tank to 65 degrees the fish would be in a block of ice.

 

[lapin]

Howdy
Do the temps drop at any certain time of day?
Could be the house heater, cooking activity, no activity or something like that since you live in a tiny place.

 

[Arcrgirl]

A 20 gallon tank has quite a bit of thermal mass and would take quite a while to change 6 degrees up or down.
How are you measuring the temperature. Does it use a probe that can be in and out of the water.
If a tiny bag of water was cold enough to lower the 20 gallon tank to 65 degrees the fish would be in a block of ice.

The bag was about the size of a gallon Ziploc and I tested the water after moving the fish to keep him warm. I have a probe that's a bit older, a cheap stick to the glass one as a backup and a digital one as well. The probe was reading 68 but since it's older I don't trust it as much as the digital one which was reading 65. I have a better probe on order, should be arriving tomorrow, hopefully that will give me more accurate measurements.

 

[Arcrgirl]

Howdy
Do the temps drop at any certain time of day?
Could be the house heater, cooking activity, no activity or something like that since you live in a tiny place.

I haven't noticed at all, it was steady at 79 until I added the fish's bag to acclimate him then it dropped. One of my heaters isn't submersible and I made sure to move it up above the waterline so it wouldn't fry when the water level rose. I have the tank in the living room on an outside wall a bit closer to the window (3 feet away) than i would like but the window is wrapped and I can't feel a draft or even a temp change until i touch the window wrap so I don't think it's the window either. My thermostat is set at 74 and that doesn't change until summer and I keep it running as long as I'm in the house and not at work:/ this is just so confusing to me why the water temp would drop so much.

 

[motortrendz]

May sound silly but what are you using to circulate the water. If the heater is heating the water on one side and you taking a reading on the other it could cause a difference and if the warmer water is sitting around the heater bc theres no movement that would cause it to cycle off too soon. Causing a lower temp in the tank. Again just a thought.

 

[Greg P]

76 to 82 degrees is a pretty big swing.

A single 100w heater is plenty to keep your 20g tank within range in your room temp of 74.
I'd try running only 1 heater for an afternoon, then the other heater the next afternoon, and see if either is able to do the job by itself, and also to rule out if 1 is staying on too long.

Adding a controller is a great idea but getting your temp more stable until payday wouldn't hurt.

May sound silly but what are you using to circulate the water.

Ya, adding a small powerhead would certainly help keep the whole tank consistent, and also help move detritus towards your filter.

 

[Arcrgirl]

May sound silly but what are you using to circulate the water. If the heater is heating the water on one side and you taking a reading on the other it could cause a difference and if the warmer water is sitting around the heater bc theres no movement that would cause it to cycle off too soon. Causing a lower temp in the tank. Again just a thought.

A good point that I hadn't thought of, but I have one heater on each side and I take the temp in the front-center and each side to make sure it isn't getting strange readings off the filter or one of the heaters isn't bad.

 

[motortrendz]

A good point that I hadn't thought of, but I have one heater on each side and I take the temp in the front-center and each side to make sure it isn't getting strange readings off the filter or one of the heaters isn't bad.

Maybe get a little powerhead to circulate the water and see if that helps.

 

[Arcrgirl]

76 to 82 degrees is a pretty big swing.

A single 100w heater is plenty to keep your 20g tank within range in your room temp of 74.
I'd try running only 1 heater for an afternoon, then the other heater the next afternoon, and see if either is able to do the job by itself, and also to rule out if 1 is staying on too long.

Adding a controller is a great idea but getting your temp more stable until payday wouldn't hurt.


Ya, adding a small powerhead would certainly help keep the whole tank consistent, and also help move detritus towards your filter.

I thought that too, the second one is more in case the one or the other crap out and i wouldn't be able to tell until i get home from work (12 hour shifts with an hour drive each way) and by then it would be too late for me to do anything. I'll definitely try running just one heater at a time and see if that helps. It might be that one of the internal settings was calibrated wrong and its messing with it.

 

[Greg P]

It might be that one of the internal settings was calibrated wrong and its messing with it.

And that would be a definite warranty issue.
Let us know what you find out from testing.

 

[Arcrgirl]

Will do! I'll keep an eye on it over the next few days and let you guys know. Thanks for all the help and suggestions!

And that would be a definite warranty issue.
Let us know what you find out from testing.

 

[Arcrgirl]

Will do! I'll keep an eye on it over the next few days and let you guys know. Thanks for all the help and suggestions!

New to saltwater tanks, after having freshwater for a few years I decided to try my hand at salt when my little brother got rid of his tank and gave it to me. It's been cycling with no fish, just cc and a couple live rocks for the last two months while I worked on trying to familiarize myself with the process and do as much research as I can when I have time before adding more to it. It's a small 20 gallon (fish tanks in tiny apartments is difficult) with an over the back filter, two heaters and an air pump. After testing the water the last few days and getting consistent neutral results, i decided to add a common clownfish to get it cycled through the rest of the way. I got home, put the bag in the tank to acclimate the temp and 20 minutes later when I checked it, the water temp had dropped drastically. 78 down to 65. I took the bag out and put it in my soup pot on the counter and slowly added lukewarm water to warm the poor fish up again while I tried to figure out what happened. The tank warmed up again and I tested both heaters separately to make sure they work and they do, I tested the water again to make sure it didn't have a negative effect and the salinity which had been stable at 1.022 was up to 1.028.
This isn't normal right? Is it possible that the lighting helps heat the water that much so by putting the bag in the water to acclimate it blocked the lights too much? Any ideas? I don't want to put this little guy in the tank if it's going to keep fluctuating that drastically with the gravity so high.

update: It kept fluctuating Sunday through Tuesday up and down in 6 degree intervals, but evened out on Wednesday. I tested each heater individually in the tank and one of the heaters never brought the temp above 72 no matter how high i turned it, even after letting it sit in the tank longer than recommended before turning it on. I'm guessing that this was the issue since after I removed it, everything straightened out and the temp has been great since. Thanks for the help and suggestions everyone!