Topic: Well I get to rethink the general plan.

[AnswersinGeneSimmons]

Well I get to rethink the general plan.

OK I have not posted here for a bit over a year.  When I was last here, I thought that I had found the right way to set up a tank.  However, I ran into a problem.

I don't know that it was a structural issue but the idea that it might be left me really cold.  So I have a tank that I am not willing to put water into.  I did not want to just put it out by the dumpster because that seemed to me to be a really bad idea.

Well, I finally found a guy who wants a snake.  So he is taking the tank away in a day or two for free.  Good for him and good for me.  still I have the chance to get a new tank.

So, given that I have something like 100 gallons worth of filter, can I do a smaller tank and still do like 50-75 small fish?

What size tank do I need to look at for that?

[LittlePuff]

What do you  want to keep? Oscars, cats, goldfish and puffers all need overfiltration.
   

[Cholly]

Some of what you want will have to do with what you consider "small". Size is relative. Give us a reference size. Some people consider guppies small. To me, under 3 or 4 inches is small. I keep fairly large fish.

[AnswersinGeneSimmons]

OK, the original plan was to do a black water tank.  So different kinds of tetras would be the main focus here.

Once I get a dozen or so fish, I might go a bit off plan and try some danios and a couple of angels.

What I am looking at here is that the filter, heater and aerator can all handle a 100 gallon tank easily.  The part that is the most probable limit is that the driftwood was based on the assumption of a 48 inch tank.

[LittlePuff]

I've always loved Aquaclears. Reliable, easy to clean, many media choices, cheap.

[AnswersinGeneSimmons]

Well, thank you very much for the recommendation.  Really.  The only thing being that I may have not be fully clear on what I was asking. 

I have pretty much everything needed for a 75 gallon tank, including a 300 gph filter (Rena XP2).

Perhaps, I should just spill and see where this goes.

Now I took quite a while to start the setup.  Part of that was that the place I got the tank also sold me a  prefab stand at the same time.  When I unpacked it, I found that it was made from pressboard.  Now a quarter of a ton of splashy water on a stand that is water soluble did not really excite me all that much.

So it took several weeks before a local thrift shop had a real wooden desk in stock.  Eventually, I was ready to star filling it up.  When I was ready, I started pouring buckets of water in only to discover that the glass was cracked in one corner.  Not badly enough to be an immediate leak but again, that is a whole lot of water to engage in possibly chancy behavior with.  By that time, it was already past the limit to return it to the store I got it from.

The original plan was for the largest and hence most stable tank that I thought I could handle.  If the store had had a 100 gallon tank, I would have done that.  So now I have no tank but I have support for one.  It seems to me that with the gear that I have, a smaller tank would still be quite stable.

Anyway, what I am asking goes to the viability of buying a tank which would be a bit smaller.

The heater is inline to the filter so correct temp water would be distributed down the length of the return tube and the heater would be on somewhat less often.

The filter would build to the lower bio load.  Instead of changing the water 4x per hour, it would do 5x per hour (for a 60 gallon tank, slightly more for a 55 gallon).

So does my thinking sound right?  Or would I have to replace more than just the tank?

If am still good to go, then I can start thinking about which tank to get.

If I get a tank which is not as tall but the footprint is the same, I would see some modest increase in the surface area to volume ratio.  Keeping the same water pump/aerator will still stir the same surface up.  I can't see how that does not help.

If I get a tank with a smaller foot print, then matters are slightly different.  The pump/aerator is stirring less surface but the ratio would be different.  I am not sure how to figure out how that changes the mixing.

Further thoughts?

[Cholly]

I'd go with the 75. Same length as a standard 55 but a wider footprint, which gives you more flexibility with fish choices if you change your mind down the line. I know that my tastes have changed considerably over 40 years. The wider footprint also gives more surface area, like you mentioned, which is always good.

Then again, given a choice, I will always go with the bigger tank. You are the one that needs to be happy with it.

Inline heaters are generally lower wattage than in tank ones, I don't think it should be much of a problem. I like inline for a reason you don't need to consider, they're where large rowdy fish can't bang on them(I was always afraid my oscar was going to break his)

Overfiltration is good, truthfully, if the current doesn't bother the fish, I believe there is no such thing as overfiltration. I run 8 to 12 times turnover in all my tanks.

Hopefully this is more in line with what you were asking. Yes, you can definitely go with a smaller tank with the filter and heater you have. With the heater, I wouldn't go too much smaller, as it will cycle more frequently and probably shorten the heaters lifespan some. Probably not a lot, but some, and some will depend on whether the thermostat is electronic or bi-metal. Bi-metal is a moving part, very small movement, but movement, it would be affected the most, but you should still get a few years of service out of it. I retire mine at ten, for normal service. Doing this I've only had three fail in 40+ years, with usually at least three tanks running.

[AnswersinGeneSimmons]

Well, the heater is an inline one but it is 200 watts so that should be enough for either a 60 or 75 from what I understand.  That and the box says that it is electronically accurate whatever that means.  Honestly, having spent some time learning electrical engineering when I was younger, I can't say that just because something is electronic that it is automatically better.

I don't follow you on an over sized heater cycling more often though.  I would tend to think that any tank cools at a uniform rate for the most part and a larger heater would have to run for a shorter time to get the tank back to where it needs to be.  Basically, it would spend more time off than it would on.  Did I miss something important there?

As far as the filter goes, I did not like the fact that they only included like half a dozen bio balls, so I went back to the store and got a box of ceramic rings to add to that layer of the filter.  I figure that the filter will only build to the bio load that I throw at it but it should be good for more than the manufacturer had in mind.  Does that sound right?

[Cholly]

Smaller tanks cool faster than big tanks, your ambient temperature will have the most effect there. Somebody convinced me a long time ago about the cycling, I don't even remember the hows or whys. I've seen bi-metal thermostats that were older than me and still functioning, but who knows the quality of the thermostat? The only thing that really bothers me about over sized heaters is the fact that the number one failure is supposed to be them sticking "on". The bigger the heater, the quicker it will reach killing temperature. I've only had 3 heaters fail in 40+ years with multiple tanks myself, but they failed the way they're supposed to, one flat died(burnt out apparently), and two stuck "on". One I caught in time, one I didn't.

You're correct on the biological filter only growing to the load, as long as there's sufficient capacity(surface area for the bacteria to grow) with a good flow of food and oxygen. I'm with you, I usually stock any area for chemical filtration with more biological media. I rarely use charcoal or zeolite, either one, but I figure, "Why leave it empty?"

[AnswersinGeneSimmons]

Well, from an engineering perspective, it makes a great deal of sense that a smaller tank would cool faster.  There are three ways for a hot thing to cool down.  Radiation can be dismissed out of hand as that is almost not even calculable for the temperatures we are looking at.  Evaporation would be fairly minor as long as you keep the lid closed.  The one that will matter most is conduction to the air in the room.

For that, what matters is the ratio of surface area to volume.  I am thinking that the four sides are what must be taken into account here as the air under the bottom rim basically never moves and the top is probably getting as much heat going in from the lamps and ballast as it might be losing.

There is a fairly simple formula for that but unless anyone is curious, I see no point in covering that right now.

As far as the heater goes, I really don't see any reason why it would cycle like that.  Consider the  opposite case of an undersized heater (say 50 watts in a 100 gallon tank).  It is going to be on 24/7 and it will only create a warm spot in the water around it.

Now if you go to a larger heater, you should get to a point where it turns off some of the time.  Going further, a really large heater should spend more time off than on because it takes some time for the tank to cool down before it gets to whatever temperature will trigger it to activate.  Then when it is on, it is heating the water faster than the heater that would be on, say half the time.  So it would be on for a much shorter time as well as off for a much longer time.

At least that is what I am thinking.  I suppose that if you put a 250 watt heater into a 10 gallon tank, that might cool fast enough to switch frequently.  With the right input, that can be calculated but that is so over the top that I doubt it ever really comes up as a situation.  In fact, I would bet that most people with small tanks are looking for a relatively inexpensive start up cost.  A heater that is considerably over spec is going to cost twice as much.  If the goal is to stay south of $200, then a $75 heater that no reputable business would recommend is not one that seems like a probable buy.