Intro And My Fishy Project - Cora

Cheers Sue I could do without the loaches altogether but since I already have one it's either keep him or give him away.

Nice list of fish. I'm quite partial to a few types of cory. Panda cory are very cute. I have some peppered cory in my temperate tanks and they are quite interesting little characters. And they fart, it's brilliant and will never cease to make me chuckle whenever I see it (not often enough).

they died seemingly inexplicably aged 5-8 months.

I was just thinking about this. I'm wondering if its because by the time you see them in the shop they're generally already quite mature. I tried to get medium sized fish to take home, a few of them were absolutely tiny.

Have just read this with a slight trigger of alarm. Thanks for the disclaimer - that's put my mind at rest.    Enjoy your evening.

My KH is exactly the same - from the tap, 1 drop of re-agent to the water turns it yellow. However, with a lump of limestone rock (Tufa rock) in the tank, it means that the water in the tank is usually around 3 because the limestone rock leaches out. After a water change, it drops to about 2 but usually increases up to 3 after a few days.

Sue's suggestion of bicarbonate of soda is probably best for the cycling process, but, once that is done, then either a lump of limestone (Tufa) rock or else coral in a muslin bag in the filter should help keep the KH higher. Once the tank is cycled, then two small water changes per week rather than 1 large water change should help too.

As for shoals, 10 is better than 6 - 6 is the absolute minimum but the fish will feel much more comfortable and display more natural and quite stunning behaviour if kept in a group of ten, so that's a good move.

fcmf posted as I was typing, but I'll post what I've written anyway 

Low KH doesn't impact on the fish directly. But carbonate buffers pH; if there is very little KH, you are at risk of a pH crash. The natural tendency of a fish tank is to become acidic - nitrate made by the nitrogen cycle is acidic as are hormones etc secreted by the fish. Several years ago I suffered a pH crash as my KH is 3, the tank was overstocked and I didn't do enough water changes to replenish the KH as it go used up. That's how I found this site, looking for help.
There are a few members who have low KH like you, and they should be able to give you some pointers. In general terms, you need something that will increase your KH. You could use crushed coral or coral sand as a substrate (except it's white not black  ), lumps of limestone rock and pieces of coral as decor; or, since the new tank will have an external filter, a bag of crushed coral in the filter. If you could source any, crushed aragonite would do as well or even better than coral as that is made of more than just calcium carbonate.


As for fish numbers, looking at your list and Seriously Fish:
Cherry barbs - at least 6 to 10
Penguin tetras - Both false penguins (Thayeria boehlkei)and true penguins (Thayeria obliqua) - at least 6, preferably 10 or more
Cardinal tetra - at least 8 to 10
Glowlight danio - at least 8 to 10
Panda cory - at least 6
Zebra danio - at least 8 to 10
Slender harlequin - at least 8 to 10
Pakistani loach - at least 5 or 6, preferably 10 or more
Bolivian ram - mixed sex group of 6 to 8

A couple of comments -
Slender harlequins aka lamb chop rasboras (Trigonostigma espei) are not common in shops. The similar Trigonostigma hengeli is more common, and often called copper rasboras. Trigonostigma heteromorpha (harlequins) are everywhere.
Pakistani loaches are also known as yoyo loaches with latin names Botia almorhae and B lohachata.

Also fcmf - "Tufa" I believe I bought some of this in a very good fish store yesterday. I should really remember this stuff - the fishies were so pretty, I was distracted... Apparently it's quite a potent carbonate so a small piece should be sufficient.

Lots of questions to answer 

Yes, coral etc will raise the pH and GH as well as KH. But not by much. As far as pH is concerned, fish can cope with a pH outside their preferred range better than a hardness outside their preferred range. I have a GH of 6 and a pH of 7.5; I can keep soft water fish that like acid pH better than hard water fish that like alkaline pH.

GH is what is meant by hard/soft water, and is what fish profiles mean by hardness. It is a measure of divalent metal ions; in natural freshwater this means mainly calcium and magnesium with some trace metals. I got the definition from my son who spent 5 years working in a water testing lab.
The reason for using aragonite in preference to calcium carbonate in all its forms is that it does contain the other minerals.


APS filters - the plastic is a bit less robust than more expensive brands so more easily damaged if you are rough. And the flow rate is less than they say. A lot of manufacturers quote the flow rate without media inside, then when media is put in the flow rate drops quite a bit. APS is one of those.
Another forum I'm a member of did some tests a while ago - those members who had certain filters attempted to measure the flow rates of their filters. The API ones gave results:
Quoted - 2000 litre per hour; actual - 900 litres per hour, 910, 1260, 1320,
Quoted - 1400; actual - 660.

As you can see from the people with the 2000 filters, their tests showed quite a variation in flow rate. In general terms, assume APS filters deliver about half the quoted turnover when there is media in the filter. The nature of the media and the cleanliness of the media will also affect flow rate.
The 1400 is a bit underpowered for 180 litres, but it should be fine provided you don't keep messy fish - that is, fish that poo a lot eg plecs and fish that leave a lot of food uneaten eg oscars.


Ammonia removers fall into 2 types, liquids like ammo-lock and solids like zeolite.
The liquid ones contain a chemical that bind to ammonia reducing its toxicity - but the complex breaks down in around 24 hours releasing the ammonia again. The main use for this type is where the water company uses chloramine as a disinfectant. Dechlorinators break chloramine down to chlorine, which they then remove, and ammonia. The filter bacteria will remove the ammonia but not instantly; the water has to circulate to them first. Until the bacteria can remove it, it is still in contact with the fish. Many dechlorinators also contain an ingredient which binds the ammonia till the bacteria can remove it. These chemicals are also sold as stand alone products like ammo-lock. They are still only effective for about 24 hours.
The solid ones, like zeolite, absorb ammonia and remove it from the water. But then they get full and stop working. Zeolite etc must be replaced before they get full. For ever. Because they remove ammonia, the tank never grows enough bacteria to 'eat' all the ammonia made by the fish. If the zeolite is not changed, once it is full the level of ammonia in the water starts to go up, and the fishkeeper only becomes aware of this when his fish start behaving oddly.
It is far better to grow a colony of ammonia eating bacteria to remove the ammonia and grow lots of live plants which use ammonia as fertiliser than to rely on chemicals. Bacteria and plants are self replicating!

Hi Sue, thanks so much for such a comprehensive answer.

Your comments on zeolite et al are what I feared: just a money-sink and prevents a safe mature colony ever getting going.

I plan to heavily plant my tank too. I'm not thinking "underwater jungle" but I do want quite a lot. As soon as I have the setup I'll give you a photo. Aquascaping will be one of the first things I do.

What you said about fish being able to cope with pH variance much better than hardness is great to know. It seems I can source some aragonite so I can put a bit of that in a filter bag in the filter.

What you said about the external filter actual flow rate is a bit disconcerting. I am going to assume that an inline heater attached to the return flow might decrease it further (even if only fractionally)?

You've seen from my wishlist that I don't have particularly messy fish, but I thought I'd mention it anyway since, as I say, there will be lots of plants too to soak up the poo!

As for the trace elements requiring replenishment, how much will aragonite help with some of these? I'm not trying to avoid the water changes of course! - I'd just like to understand better.

Officially, things like calcium carbonate are insoluble in water. In practice, they dissolve slightly. They won't make very much impact on hardness etc, maybe raise it a degree or two. Tapwater also contains more than even aragonite.
A few years ago I did a small experiment. I took 2 plastic tubs, filled one with just water and the other with water and a layer of crushed coral in the bottom. I left them for a week then measured pH, KH and GH of both.
GH and KH were both 2 german deg higher in the coral tub than the plain water tub; pH was 0.2 higher.
The plain water tub was a control; always compare the test sample to one that has not has anything added to it but treated the same otherwise.

I'll leave plant experts to tell you what plants need in terms of fertiliser.

I must say, Sue, you are definitely tickling my science fancy  All this talk of controlled experiments and testing

Impatience is one of my vices but I can see now that preparing the tank can be quite fun too.

My plan with the plants is to use liquid CO2 and fertiliser for the cyling stage, as there'll be no food source. They are all easy growers with little requirements so once the tank is established I don't believe I will need to fertilise or provide extra CO2 - however I'm happy to take advice on this.