# Inch/gallon rule



## thapsus (Feb 17, 2005)

What do you think about this rule? And how does this rule apply to your aquarium? Do you have more fishes than you should according to that rule and everything is allright or do you have less fishes and your tank is allready overstocked? 

1. Your tank size?
2. Fish inches?
3. Nitrate rate max.? 
4. And how often you change water and how much? 
5. Do you have plants? How much?




My answers:
1. 24 us gallons
2. 74,4 inches
3. 0
4. third once a week or two weeks
5. Yes, lots of plants. 

So as you can see, in my case this rule don't seem to apply very well. Before I thought that plants don't use much nitrate. Now I know they actually do use and very much too. Maybe it affects too that all my fishes are very little or kuhli loaches. 



Just curious...


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## Kev Rob (Mar 25, 2005)

Its a rule of thumb. It depends on so much!

I have my pond wish over wintered in a tank that is too *small* for them. I have it heavily filtered, and do massive water changes every week. Lots of work. But never had any problems with it. Knock on wood.


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## [bt] (Mar 3, 2005)

My tank is 8gal and I have 12" of fish in it (12x1" fish).

This seems to be fine. I do 25% water changes every 5 days or so, keep the surface of the water broken and moving, give them a little current to swim against and fish out the unwanted food and bits of plant daily.

I do however have a feeling that I'm pushing it slightly. They have more than enough room and seem happy, but I'm always keeping my fingers crossed!


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## Thunderkiss (Mar 19, 2005)

The 1"/gal rule is merely a generalization. Many other factors "should" be taken into account yet aren't.
It certainly doesn't apply to goldfish or koi or anything marine.
It shouldn't apply to anything but the smallest of fish, and doesn't in any of my tanks. Anything large should be factored by its own rules based on waste output, length, eating habits, weight and territorial requirements.


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## Ron the handyman (Jan 18, 2005)

I find that the more filtration you have the more fish. filtration, filtration, filtration,


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## garfieldnfish (Jan 18, 2005)

I have a total of 8 tanks actually housing fish permanently. Plus one pond snail tank, one brine shrimp tank and one plant tank, currently containing x number of skirt tetra fry. The 2.5 gal skirt tetra fry/plant tank is way over stocked as is my 29 gal with 1 gourami, 3 corys, 2 SAEs and 7 skirt tetras, but the values are optimal, lots of plants and weekly water changes of 30%. All my other tanks are under the inch/gal rule, but I still do weekly water changes.
The inch/gallon rule is only a guideline. Some fish like goldfish and plecos need more space because they are heavy poopers, some small narrow bodied fish can be be housed in less space, like neon tetras, glolights, rasboras, minnows, etc. And some fish need more swimming room like giant danios then the inch/gal rule would normally give them. For each fish I now do some research before getting it and then set up the tank for what the fish needs.


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## Damon (Jan 18, 2005)

It should be called the rule of dumb. There are many factors that determine fishload. While filtration is key, it becomes inert depending on the size and spacial needs of your fish. Putting a high powered filter on a 10 gallon is useless if you want 25 neons in there. There just isn't enough room for them. Some fish grow large. Again adding filtration won't help. Common sense and question others experience is the only rule of thumb I follow.


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## fish_doc (Jan 31, 2005)

That rule was set up years ago with the theory that most stores only stock fish that fit that catagory. small tetras, guppies, platies, etc.... But with the advancement of the hobby and bigger tanks stores now stock large catfish, pacus, and such that blow the mass of the one inch rule out of the water. (no pun intended)


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## Osiris (Jan 18, 2005)

it raelly does depend, as in Saltwater tanks you so do not wanna follow that rule but in african cichlid tanks you usually wanna overstock in a mixed species tank..so u break the rule again, lol. I think it's aimed more at community type fish, like guppies, tetras and stuff, like Fish_doc just said...


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## DavidDoyle (Jan 18, 2005)

It also depends on the specific fish involved and how well they interact and how territorial they are. My community 45 was fine and a bit overstocked til the angels paired off. Suddenly a tank where the fish coexisted very well for many months became a battleground.
By most standards my 75 is overstocked with 40 cardinal tetras, 8 sterbai cory, 4 SAE at 5-6 inches and finally 5 clown loaches, the largest of which are between 6 and 7 inches. However, I have very few deaths in this tank which is heavily planted, way over filtered and gets weekly wc of 35-40%. The fish all coexist very peacefully.

I rarely test any of my tanks for anything except for the hi tech 50 gal co2 added one. There I test phosphate and nitrate now and then. Usually I find I need to add both of these items because they are way too low.

All my tanks pretty much get a 35-40% weekly change. The two exceptions are the discus whick get 3-4 changes/week and fry tanks which get 10-15% daily.


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## thapsus (Feb 17, 2005)

Um, what do you achieve by filtrating more? Is this only because of oxygen? Nitrate is the same what ever you do...


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## Ron the handyman (Jan 18, 2005)

I have 30 tanks and the largest is a 125 x 2  two emperor 400s and two regent 330 
on each one tank has 6 oscars two fire heads 6 jags 3 convicts two pleco's one blue eye and three jack demseys. most are full grown and the water is clear, 50% change every two to three weeks due to my work schedule   R.


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## Osiris (Jan 18, 2005)

just self confident here with more filteration, when overstocked helps catch debris and biological filteration, in saltwater tanks it's not uncommon to see a tank do 30X turnover rate since some species thrive on it. I have noticed clarity in the tanks that are overstocked since i have usually double the recommended filteration on it.


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## thapsus (Feb 17, 2005)

So how, lets say 600 l/h and 1200 l/h filtration are different? What do you achieve by filtering water faster?


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## fish_doc (Jan 31, 2005)

Its not that you are filtering it faster but you are giving the tank twice as much surface area to complete the nitrate cycle with any waste. It is kind of like doubling the size of your local dump. You can then supply service for more people.


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## TheOldSalt (Jan 28, 2005)

That's all fine and dandy until the power goes out.

On another note, I'm sure that Ron's 50% biweekly waterchanges are what keep his fish going, not the extra filters. The filters help, but 21 big adult plecos and cichlids in a mere 125 gallons? Let's see 'em make it without the water changes.


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## Ron the handyman (Jan 18, 2005)

Generator


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## fish_doc (Jan 31, 2005)

Power going out will hurt almost any tank. Its a saltwater tank owners nightmare because of the amount of equipment used on them.
Like Ron said generators. I have a generator also and have used it many times. We were without power for 4 days last year after a storm.


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## fishfreaks (Jan 19, 2005)

we used to apply this rule, but then pple here told us that it was only considerable for smaller fish, needless to say that was the end of that rule!


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## Osiris (Jan 18, 2005)

yea man that would suck losing power on the SW tank, we usually only lose power when tornadoes go through towns in summer here, i remember sittin for couple hrs with a wooden spoon stiring last summer...i am investing in a air pump battery operated ths year..


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## UgLy_eLf (Feb 26, 2005)

If the power goes out Downtown (And I live downtown) its up within 2 hours, OhHh Yeah Viva La City.


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## Lexus (Jan 19, 2005)

My answers:
1. 55G 
2. a lot! all thats in my sig, around 60 fish in my 55G. Inches may be double so I'll guess 100"
3. 40 max and its rare to hit it. 
4. once a week or so, about 40%
5. No live plants


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## thapsus (Feb 17, 2005)

> Its not that you are filtering it faster but you are giving the tank twice as much surface area to complete the nitrate cycle with any waste. It is kind of like doubling the size of your local dump. You can then supply service for more people.


Yes, so you will not get nitrite in your tank so easily....? It will not affect to nitrate rates. And before you'll get nitrite you get probably massive amounts of nitrate. Albeit nitrate is not deadly even in bigger amounts to many fish species, I don't want them to suffer from it. 

I still think that biggest amount of bacteria is living in bottom sand, not in filter. Current in filters is often too fast for many bacterias to attach. 

So I still can't understand how you benefit from filtrating more. :?


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## [bt] (Mar 3, 2005)

Thapsus.
Higher filtration means you're pushing more water through a larger surface area of filter material. Yes, the water may flow faster, or it may not.

What matters is the surface area across which the water flows. 

Image emptying your tank onto the floor of a warehouse and measuring the area it covered. Let's says it's 36m2.
If you're filter can do 18m2 an hour, it'll take two hours to filter your tank completely, although you'll effectively be putting the same water through twice.
If your filter could do say 50m2 an hour, in just one hour you'd theoretically be filtering your entire tank water 1.5 times.

As for flow rate, I don't think it really matters. You're correct in thinking that the flow is often too fast for filters, but if the surface area of the filter medium is higher it doesn't matter about a high flow because the filter WILL be sufficient enough to filter the water. I'd imagine that the faster the flow, the higher the surface area required for effective filtration.

Now, onto tank surface area, ripples and oxygenation.....


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## fish_doc (Jan 31, 2005)

> If the power goes out Downtown (And I live downtown) its up within 2 hours, OhHh Yeah Viva La City


There are 150,000 in the city I live in but the storm knocked out power for 3/4ths of the city. I am in northern Il and we had power crews come in from all over the country. TX, FL, AL, NY just to name a few. Because the damage was so widespread throughout the city it never ranked as a federal disaster. It was like .50 short per sq mile to be considered. 


As far as the filters and water flow. The bacteria actually grows better with water flow. That is why they have ugf. The bacteria only grows on the top of the gravel. With a ugf it expands to deep withen the substrate because of the added water flow within the gravel.


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## malawi4me2 (Jan 18, 2005)

I don't believe that rule is applicable to anything but the smallest fish. And even then, there are limits... Like one neon shouldn't necessarily be kept in a 1 gallon tank because that's not big enough for their schooling behavior. But I certainly couldn't have a 10ft fish in my 4ft (120g) tank, nor should a 10" oscar be kept in a 10g tank! 
-120g Tank
-Approximately 44" of fish length
-WC once per week; Nitrates<30ppm
-Lost of Jungle Vallisneria, Java Ferns, and Annubias barteri


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## flynngriff (Jan 19, 2005)

I've always thought that the inch/gallon rule is just fine for people that don't want to get as heavily into the hobby as the rest of us. They generally have smaller tanks, and smaller species of fish, like the smaller tetras or guppies. As long as the fish don't get to be more than 2 inches or so, it works fine for people that don't want to or have time to research the bioload of their fish. It helps keep them from getting overstocked. Anything that helps with that is a good thing. It just breaks down when you start talking about larger fish. How many inches does a 4 inch severum count as? It's 4 inches long, but 3 inches tall... Is it a 12 sq. inch fish? The rule just doesn't work for larger fish.

Like it or not, a lot of people aren't going to research their fish, so giving them a basic beginner's guideline like this is a good idea, IMO. As long as this guideline is explained to them as not working on anything but small species, and that a lot of those fish need to be in schools, it can't hurt.


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## ravekiss (Jan 20, 2005)

1. 20G High
2. Current Size 18"....Adult Size 38"
3. 0 Nitrates
4. Once a week...20%
5. No Live Plants...about 9 plastic plants

Running a Aqua Clear 50/200 filter. I really want a Kuhli loach or 2 but I dont know if my tnak can take it.


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