The old Heater question.

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I would go for two heaters in a 90g. One could create uneven temp areas unless your water circulation is exceptional. Also, if one heater fails then the other could keep you out of trouble until replaced. Also you could consider controlling your heaters from a separate external control box which uses a probe positioned at the centre back of the tank. I've attached a photo of mine (I know I've posted this before) but it's brilliant at controlling the tank at an even temp. They're not expensive.
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The first question is how far will you need to heat the tank from ambient room temperature?
 
I have a Fluval E200, works pretty good, otherwise I like cobalt neo-therms. I would get 2 100w or 150w heaters.
 
Thanks guys! yeah I would say that the ambient is probably anywhere from 74 to 68 at night.

so if I do go with 2 heaters, the correct wattage for each is the total sum of wattage I would need in the tank? like I think the E200 is for tanks up to 65 gallons, so that would be a total wattage of 300 watts for up to 120/130 gallons (just over my tank size).

Im trying to work out how to choose the correct wattage for my tank if I have to break it down into two heaters.

I also think I like the additional control sensor regardless, I cant see that being anything but a +
 
Thanks guys! yeah I would say that the ambient is probably anywhere from 74 to 68 at night.
So, if the ambient temperature drops to 68 you properly want to consider getting something that can heat you 20F so you can do things like treat for Ich.

so if I do go with 2 heaters, the correct wattage for each is the total sum of wattage I would need in the tank? like I think the E200 is for tanks up to 65 gallons, so that would be a total wattage of 300 watts for up to 120/130 gallons (just over my tank size).
The first thing you should do is ignore the manufacturers recommendations on the box and use a heater calculator. There is one here.

Im trying to work out how to choose the correct wattage for my tank if I have to break it down into two heaters.
Just divide the required heater by 2.

I also think I like the additional control sensor regardless, I cant see that being anything but a +
Given the absurd failure rate of the internal thermostats, heater controllers are excellent investments. Between my wife and I we have lost 3 tanks of fish to heater malfunctions.
 
The calculator says 15 watts for a 90 gal with 10 degree F difference. Seems way off to me.Better to stick to the manufacturers recs. However, different manufacturers use different ratings. Eheim seems to call for half the wattage of other brands.
As to losing tanks to heater malfunctions, it would only happen if you have too much wattage to start with. As to the oft repeated claim that ich is caused by a drop in temps, this is false. You will only get ich if ich is in the tank. It has nothing to do with temperature.
Regardless, better to be a little under than over as far as wattage goes. Most fish can be kept at cooler temps than is normally recommended. In fact there are lots of reasons to do so. A few of which are, higher dissolved oxygen level, slower bacteria growth (including pathogenic types), and longer life spans for the fish.
There are few types of fish such as discus that require high temps, but the majority of fish we keep won't be harmed by a drop to 68F. These same fish are likely to die if the temp goes to 100F.
The ideal heater would be one that never shut off. It is the on and off cycling that eventually causes failure. This was true with the old hang on backs which used contact points (I am still using mostly these) and the newer types of today.
 
So, if the ambient temperature drops to 68 you properly want to consider getting something that can heat you 20F so you can do things like treat for Ich.


Thanks Dalto for answering all those pieces !! Can you please just explain to me the comment above about heating to 20F?

Also I used the calc and got the following results, so going by the recommended wattage and the comments I rounded it up to 100W? that doesn't seem right? I was going to get 2 x 150W's at least?

Tank sizes:

Sides Walls
Length 18 inch Wall thickness: 0.5 inch
Width 36 inch Top thickness: 0.19 inch
Height 32 inch Bottom thickness: 0.5 inch
Materials and temperature difference:

Wall material: GLASS
Bottom support: WOOD
Temperature difference: 10°F
Results (calculated heater power):

Break even wattage: 71 W
Recommended minimum wattage: 80 W
Notes:

Break even wattage: This is the heater power required just to maintain temperature at the specified difference. It does not include the power required to heat the tank from room temperature to the desired temperature.

Recommended minimum wattage: You need to supply a heater at least this big to heat your tank. If it were me, I would take this value and round it up to the next available heater size.
If you get a surprisingly large or small value, you may want to check that you've entered realistic values for your wall thicknesses and the temperature difference. You may also want to check that you've used the units that you think you have.
 
The calculator says 15 watts for a 90 gal with 10 degree F difference. Seems way off to me.Better to stick to the manufacturers recs.
Assuming 1/4" glass the calculator shows 147W for me at 10F. Are you sure you keyed the data correctly?

As to the oft repeated claim that ich is caused by a drop in temps, this is false. You will only get ich if ich is in the tank. It has nothing to do with temperature.
The point I was trying to make was not that having a low temp causes Ich. It was in the event you need to treat for Ich you need to be prepared to raise the temperature higher than normal.
 
Better to stick to the manufacturers recs. However, different manufacturers use different ratings.

Regardless, better to be a little under than over as far as wattage goes. Most fish can be kept at cooler temps than is normally recommended.

The ideal heater would be one that never shut off.

Hey Bill thanks for the reply also, so with the comments you made above and the fact that I am really drawn to the Fluval E series, looking at amazon they have 100W@30G so 2 would be 60G (just under my 90) and the next size up is the 200W@65G, which totals over my 90G.

So my question back to you would be 2 x 100W or 2 x 200W?

Thanks
 
Thanks Dalto for answering all those pieces !! Can you please just explain to me the comment above about heating to 20F?

Also I used the calc and got the following results, so going by the recommended wattage and the comments I rounded it up to 100W? that doesn't seem right? I was going to get 2 x 150W's at least?
Oops, you have a super tall 3ft 90, not a standard 90. It because you have 1/2" glass which serves as an insulator. Most wooden stands are open on the bottom though.

My comment on 20F was that when treating for Ich, the standard treatment is to raise the temperature. If you start at 68 and need to raise the temp to 86+ your heaters need to support that. Now, to be totally fair, you could always add a heater in the event you actually got Ich in the tank but since it is fairly common I like to accommodate it upfront. There are also some downsides to having extra heating capacity available.

Traditional recommendation guides would probably tell you to that 250W was appropriate for 90g.
 
Assuming 1/4" glass the calculator shows 147W for me at 10F. Are you sure you keyed the data correctly?


The point I was trying to make was not that having a low temp causes Ich. It was in the event you need to treat for Ich you need to be prepared to raise the temperature higher than normal.


Well you can see the numbers i put in as I quoted the results above and I didnt get 147W at 10F? not sure what im doing here, but the result always comes out the same.

This is the output copied directly from that page.

Tank sizes:

Sides Walls
Length 18 inch Wall thickness: 0.5 inch
Width 36 inch Top thickness: 0.25 inch
Height 32 inch Bottom thickness: 0.5 inch
Materials and temperature difference:

Wall material: GLASS
Bottom support: WOOD
Temperature difference: 10°F
Results (calculated heater power):

Break even wattage: 66 W
Recommended minimum wattage: 74 W

TBH I just searched for a couple of different calculators and they came out at different values.. ??

I think it will just have to be a couple of 200W's
 
Well you can see the numbers i put in as I quoted the results above and I didnt get 147W at 10F? not sure what im doing here, but the result always comes out the same.
I got different results because I used standard 90 dimensions. Your tank dimensions are totally different than I thought.
 
SO do you guys think 2 x 200W's will be ok? if you do the math I guess I only really need 270W total, but I dont see too many 150W heaters that have the digital display and are rated..
 
SO do you guys think 2 x 200W's will be ok? if you do the math I guess I only really need 270W total, but I dont see too many 150W heaters that have the digital display and are rated..
What is the advantage of a digital display? Is the heater going to be somewhere where the display is visible?
 
E200's and Cobalts come in 150w.

You guys are making this rocket science, I have a single 300w heater on my 150g tank and it works. I will be getting 2 200w heaters.
 
E200's and Cobalts come in 150w.

You guys are making this rocket science, I have a single 300w heater on my 150g tank and it works. I will be getting 2 200w heaters.

not trying to make this too difficult :cool:, just want to make sure I get the right equipment. I understand that I could just get one heater, but after all the reading and research I think that the dual setup is the way to go (as you mention you are moving two).
These types of heaters arnt cheap so i want to do the right thing straight off.

The Fluval E series do not come in a 150w which is why I was asking, and if I wanted to go with the equivalent Cobalts on a double heater setup, I would need 2 x 200w according to their specs and they are out of stock mostly everywhere I have looked.
 
not trying to make this too difficult :cool:, just want to make sure I get the right equipment. I understand that I could just get one heater, but after all the reading and research I think that the dual setup is the way to go (as you mention you are moving two).
These types of heaters arnt cheap so i want to do the right thing straight off.
Yeah go dual for sure, it just seems to me that they spend all this time under rating filters then go an say you need like 800w for a 125/150g tank when I don't really think it works like that. I have 300w on a 150 and it heats it to 80 just fine. Would it go to 86 for ick? Idk maybe, am I going to get 400w eventually, yes, but mainly because I don't like glass heaters with stupid inaccurate dials, am I going to get 3 200w heaters like they suggest? No.

The Fluval E series do not come in a 150w which is why I was asking, and if I wanted to go with the equivalent Cobalts on a double heater setup, I would need 2 x 200w according to their specs and they are out of stock mostly everywhere I have looked.
Yeahhhhhh they were kind of blowing up or something so they are fixing them before making anymore. Get 2 E200's, but know they are still glass. Other wise 2 Aqueon pros on a Cobalt heater controller would work.
 
I would go for two heaters in a 90g. One could create uneven temp areas unless your water circulation is exceptional. Also, if one heater fails then the other could keep you out of trouble until replaced. Also you could consider controlling your heaters from a separate external control box which uses a probe positioned at the centre back of the tank. I've attached a photo of mine (I know I've posted this before) but it's brilliant at controlling the tank at an even temp. They're not expensive.
View attachment 250347


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I had a hard time finding any sutable heater controlers and was just going to give up and get a reef keeper? Only ones I could find was a pro heat which I couldn't find anything about and a Finnex.
 
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