New To The Forum

Hey everybody! Glad to be a part of such a great community. Currently I take care of two fish tanks fairly small in size, one for myself and one for my girlfriend.

Her tank is just a small 15 gallon tank that is only going to house small fish and not too many of them.

Currently it just has a hang on the back style filter, filtered with carbon.
And the residents are 2 Zebra Danios and 3 Oto's to help with algae control.

My tank was 30G gallon breeding ground for my guppies, but last spring the tank broke and since then I had to bring all of my fish into a smaller 20G tank. There where a lot of losses so right now it just has a hang on the back carbon filter, and there are 3 female guppies, 1 male guppy and a bristlenose pleco that is still growing. I realize the need to get a bigger tank again for the pleco so this spring I am trying to clean out a 55G that I have and get it setup.

For the current tank situations I did have one quick question, should I be using something other than carbon for the filtration? I understand that the carbon doesn't necessarily need to be replaced every month like the manufacturing companies want you to believe but I also struggle with being able to clean the filter to make it effective again.

SO what could I replace the filtration media with and does anybody have any suggestions on a container for the filter media? Both of the hang-on-the-back filters have the carbon bag and then another black foam piece for bacteria to grow on.

Hey Sue thanks for the suggestion! I will have to try and do what you said to switch to sponge. How would I buy a piece of sponge though? All I can seem to find is sponge filters, and covers for the filter intakes to not suck up fry and shrimp.

As for her tank we just added the Oto's recently and so in another month or so we were going to introduce more Danios. Originally she did have 6 but there were a lot of unforseen problems in the tank. Surprisingly the two in there seem to be enjoying themselves quite a bit.

I am actually US based, but I wasn't able to find many helpful US based fish communities. I'm sure they exist but I couldn't find them. The carbon comes before the black sponge, so I will need something with larger holes.

And actually I re-read your comment about the danios, and might actually think about bringing them into the larger tank when I have it. Do you or anybody else have any suggestions for fish that could be happier in that environment? The tank is pretty long and tall for a 15G but lacks depth.

How big is the black sponge compared to the space where the carbon bag sits? If a black sponge or even 2 would fill the space, you could use extra black sponges. Or even look at the section in the store for canister filter spares. Canisters usually have a sponge layer somewhere inside.

Can you find the hardness of your water as well, please. That is more important to fish than pH. You can buy testers but it is much cheaper to look on your water supplier's website. If American companies are anything like British ones, they'll say something like 'slightly hard' then give numbers in several different units. It's the numbers we need, and the unit that each number is in. If the website also gives something called KH or alkalinity, make a note of that too. British water companies sometimes give the hardness separately, others hide it in the water quality report.

With pH, test freshly run tap water and also let a glass of water stand for 24 hours then test that too. It is common for water suppliers to pump carbon dioxide into the mains water and this alters the pH. It gasses off when the water stands. The water in the tank has degassed, so testing a degassed sample of tapwater is a better comparison.
The pH of the tank and degassed tapwater should be very similar unless there is something in your tank to alter it. For example, wood can lower it, limestone rocks can increase it.



In that case, ignore more black sponges as an option. Have a look round a biggish store and see what filter accessories they stock. A sponge can be any make for any style of filter as long as it is slightly bigger than the gap the carbon sits in so it can be trimmed down to a perfect fit.

Since tapwater hardness doesn't usually change much, even if it is well water, you could take a sample to a fish store and ask them to test it. But be sure to get them to write down the numbers and the units.

Ah but, 75 to 85 ppm of what? In the UK, it could be ppm Ca (calcium), ppm CaO (calcium oxide) or ppm CaCO₃ (calcium carbonate). This is how annoying hardness is with all it's units!
For example, my water supplier gives my tapwater as 34ppm Ca, 85ppm CaCO₃, 5.95 degrees Clarke, 4.74 German deg and 8.5 French deg. And moderately soft.

If your 75 to 85 ppm is CaCO₃, it is roughly the same as mine which my water supplier classes as moderately soft.
The 60 to 80 ppm Ca band is moderately hard.
And if it's CaO, that's somewhere between moderately soft and moderately hard.

If you could find out what the ppm are it would help enormously. If it helps, home test kits measure ppm CaCO₃.



My tapwater pH is 7.6 freshly drawn. It drops to 7.4 on standing 24 hours. If those ppm are in CaCO₃, your water is very similar to mine. Because hardness is more important than pH, I can keep soft water fish easier than hard water fish.


And if the hardness is ppm calcium carbonate you are quite likely to have low KH as well. This doesn't affect fish directly but it can allow the pH to drop. KH is a measure of the amount of carbonate; carbonate is a buffer. It reacts with acid and keeps the pH stable. Nitrate, the end product of the nitrogen cycle, is acidic as are lots of other things secreted by fish. The natural tendency of a fish tank is to become slowly more acidic. The presence of carbonate in the water stops this. But with low KH, there isn't much carbonate to start with and it gets used up. Once it's gone there is nothing to prevent a pH crash. If you do have low KH you need to do water changes every week without fail to replenish the carbonate.
I found this forum back in its previous incarnation in 2006. I was a bit lazy with water changes and discovered my pH had fallen off the bottom of the tester scale - it was below 6.0. This is where I found out about the implications of low KH. I have had no problems now that I do water changes at least once a week without fail. Learn from my mistakes 

With nitrate the aim is to stop the level going higher than the tapwater level plus 20. How fast nitrate goes up depends on a few things such as the amount of fish and the amount of food that goes into the tank. And live plants also help keep nitrate down as plants use ammonia as food so there is less to be turned into nitrate by the filter.
Frequent water changes also remove things we can't test for such as fish hormones. Nitrate is an indicator of the water conditions in general - if that's high so is everything else.

If you do buy a hardness tester it will probably come as a pair, GH and KH. Or take some tapwater to a shop and ask them to test - but make sure they give you the full unit as well as numbers for both of them.
KH only comes in 2 units - ppm (aka mg/l) and German deg (aka degrees of hardness). Mine is 3 German deg (54 ppm) which is why I had that pH crash. It gets used up quite quickly.