Bigger Tank

Hi,

I have the Interpet Fish Pod 120L. I wrote a little review here.

I uploaded a short movie featuring the tank, but being honest you can't see much of the tank, only the inhabitants.

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I think when people talking about bigger tanks being easier, they mean easier than 25 to 30 litre tanks which are often overstocked with unsuitable fish.
The main advantage to larger tanks is that they can take bigger fish than small ones. I started out with a 60 litre tank, then got a 125 litre as well (much to my husband's dismay as he assumed it was a replacement). The 60 litre started to leak and was replaced by a 50 litre, then I replaced the 125 with a 180.
I currently have emperor tetras in the 180 which I could never have kept in the 125. The 50, which has the same footprint as the 60, has the small fish.
The downside to bigger tanks is that for the same % water change, you have to remove and refill more litres.

Your water is very soft as well, if I remember correctly?

Unless you do something to increase your KH, it won't matter the tank size you'll still have problems with low pH. But a filter for a 190 litre tank will have plenty room inside for crushed coral which would make it easier to keep the pH stable.

Of course you could always keep really acid loving fish in your water. For example, most of the less common apistogrammas would suit it perfectly.

hi, your right sue i have many probs with low ph, i have no probs for months then a sudden crash and then my probs start, I'm going to get some crushed coral { i did get some crushed shells from pets at home ). if this stabilises my tank then i will prob go for a bigger tank too as i find fish keeping very rewarding when they all happy. i even had some fry a couple of weeks ago but they all died when i had my water probs again ..   

hi fcmf, what is tufa rock,is it used for calcium or something

Tufa

Do you mean this crushed coral? If you do, that's fine as it also contains aragonite which is good because that adds the magnesium that coral alone lacks. Naturally hard water contains both calcium and magnesium.

I would start small. You don't want to change things too quickly. Monitor the water for pH and both GH and KH and when they reach the level you want, don't add any more until it starts to disappear (very slowly). If you want soft water fish, aim to keep the GH at or below 8 german degrees.

as a rough guide i have a about 2 to 3 desert spoons in both my external filter so about 6 spoons in total  for a 260 liter tank , althow i have just noitced recently that my tank ph was droping slightly but put this down to some coral haveing washed away in filter cleans etc but it had been in there about 6 months or more .

Calcium carbonate (oyster shells, coral, limestone etc) is officially insoluble in water. All this really means is that it doesn't dissolve like a spoonful of sugar in a cup of tea. It dissolves very slowly in water.

The oyster shells in your filter will be dissolving very slowly, and the water passing though the filter carries the dissolved calcium and carbonate throughout the tank. It dissolves at the same rate all the time, but you do water changes which will remove some of the dissolved mineral and then it will build up again before the next water change. This is one reason that in this scenario, two smaller water changes a week are better than one big one - less fluctuations.

Over time, the amount of oyster shell will decrease as it dissolves. This means less calcium and less carbonate going into the tank. The oyster shells need topping up every so often to keep the water levels constant.

pH is tied up with calcium and carbonate. As they go up, so does pH.

If you reduce the amount of oyster shell in the filter, the calcium (GH) and carbonate (KH) being put into the tank water will decrease. There will be less calcium and carbonate dissolving so the level will stop going up as quickly - but the water changes remove some so that the levels will start to drop from what they are now. They won't go back to the tapwater level unless you remove it all.
And because pH is tied up with GH and KH, that will start to drop as well.

This is where trial and error comes in. You have to try different amounts of shell to find how much gives the pH, GH and KH you want.