Can you more experienced guys take a look at my stocking list (in sig) please and let me know what you think. I have inhereted (saved) some fish from a friends tank but not altogether certain about how far overstocked I am now.

Water stats are:
Amonia 0
Nitrite 0
Nitrate 20pp
PH 7.8
Temp 29

All fish look happy enough and water is clear and sparkly! Just a bit concerned after it took a couple of weeks to sort a nitrite spike out last month (all has been well since then)

You've got around 60 inches worth of fish in just over 30 gallons of water. That's higher than a lot of people recommend, generally, but the filter is keeping up, so I'm assuming the tank is sufficiently mature. 1" per gallon is the usually starting recommendation - it keeps people out of a lot of common trouble, but 1.5-2" with sufficient filtration is possible in a mature tank.

The serious problem I see is that there's a number of schooling fish that don't have enough members of their own species. All the tetras, danios, rainbowfish, and the corydora catfish (I'm assuming the bronze catfish is a bronze cory) should be kept in groups of 5-6+. Corys are more active in bigger groups, and in my experience tetras and danios can become bullies when on their own or in small groups. You really don't have room to increase those numbers, though.

Are you able to calculate your turnover rate for the filter? You may need to go significantly higher than the typically recommended 5x rate if you are stocking 2"/G I would think.

~~waterdrop~~

aye, it's not so much the numbers of fish but the combinations that need a little bit of work.

2" per gal is manageable with good maintenance and filtration, without these you are heading for a bit of a distaster.

i would try to re-home some fish to the lfs or to another dedicated hobbyist and then increase the numbers of some of the shoalers so they'll be happier.

Absolutely; cut back the different species and up the numbers of those remaining. Have several groups of 5 or 6 and you'll see the difference in their behaviour. Less stressful, too.

Don't want to high jack the thread but can you possibly tell me more about the 'recommended rate'?

TBH, I've always payed less attention to the turnover rate than the amount of media the filter holds. I have a planted tank and have never had any problems with a turnover rate of 3 or 4 times.

i have 8x an hour turnover on my tank the more the better really

This post has been edited by dave1987: Jul 9 2008, 01:35 PM

I assume the 'x' is volume of the tank?

Sorry again for getting off topic...

It is indeed.

the 'X' means 'times' the mathematical calculation. so if you have 5x turnover, then turnover is 5 times the volume of your tank.

e.g. tank of 20l, to turn it over 5 times an hour (5x20) you need a filter capable of pumping out 100 litres per hour.

Yes, and just to clarify for pixel:

I believe both vinylman and dave are describing aspects of filtration choice that are well within the healthy averages that we read about here on TFF. vinyl is describing that fact that a well planted tank (sometimes we're talking 70% of the substrate covered with plants here - a densly planted look) will do a lot of natural biofiltration outside of what the filter is doing. In fact, the heavily planted tanks can even be somewhat vulnerable if the plants were to die, as the filter may have died off quite a bit due to lack of ammonia to feed the bacteria. But as long as everything is kept healthy in a planted tank it is a wonderful sort of environment. In a different way, dave is noting that its not that unusual to see 8x or even 10x turnover discussed, either for non-planted tanks with messy fish, or in planted tanks where the currents are kept under control and don't disturb the plantings too much.

So, like any number of other guidelines, the "5x recommended guideline" is just a sort of "starting point for consideration" thing. As vinyl mentions, media capacity is also an important difference between filters. Generally, but not always, we see a stepwise increase in media capacity as we progress from internal filter to HOB, from HOB to external cannister type, and from external canniter type to external sump. Having greater media capacity can buy the fishkeeper larger room for error when changes occur and can lengthen the time between necessary cleanings. At one extreme is mother nature, with often nearly infinite "media capacity" on a per fish basis. At the other extreme is the hobbyists limitations of money and maintenance effort for what is actually needed for their number and size of fish.

(looking back I'm not sure if this claified or muddied, lol)

~~waterdrop~~

Perfect.

When I bought my 60l tank, I got a Fluval 2+ filter for it - just because it was recommended by the LFS. I think this filter is doing a good job but I didn't know of the flow rates etc so it's good to get some background knowledge.

Thanks for clearing things up.

to avoid detracting from the point, could someone pm me and tell me what turnover is? or means? or whatever?

Turnover just refers to how many times per hour the filter will process the full volume of the tank. All filters have a gallons per hour rating. The 5x recommendation just means you want the filter to process the full volume of the tank five times per hour - a 20 gallon tank will want a 100 gallon per hour filter, and so forth.

Personally, my tanks are all around 10x turnover.