New Tank Advise Please

175 litres is a nice tank size. I got a 180 in January 

Carbon doesn't need to be used all the time except in certain circumstances. It removes chemicals from the tank, but only those that bind covalently. So it doesn't remove things like ammonium (and ammonia is almost all in this form) nitrite or nitrate. It does remove tannins (the brown stuff) that leaches out of bogwood; and medications when treatment has finished; and any odd smell you might notice. It will also remove organic waste products from the fish, but then so will water changes 

You don't need to use salt either. It is bad for some fish. The use of salt arose many years ago as it mitigates the effect of nitrite. But since there should be no nitrite in the tank, you don't need it. It can help during fish-in cycling to counteract nitrite, and it can help to treat whitespot in combination with high temperatures.
Because of its use before the nitrogen cycle was understood, a lot of old time fish keepers still use salt and pass that information down to newcomers, who pass it on .... and so on.

Have you set the new tank up yet? And do you intend keeping the 90 litre running? You can set the new tank up quickly and safely using media from the 90 litre, but rather than go into all the alternatives, once I know your plans for the 90 litre I can tell you the simplest way to set the new tank up.

Nutrafin Cycle contains the wrong species of nitrite eating bacteria. The people who discovered which was the correct species copywrited, or whatever, its use so no-one else can use the right bacteria. I wouldn't bother using it as besides having the wrong nitrite eaters it is one of the products that I've never heard of anyone saying it actually worked for the ammonia eaters either.

Too many water changes and gravel cleans won't affect the cycle. Yes, some bacteria live on the gravel but the vast majority live in the filter in the biofilm which is tightly bound to the surfaces in there. The only way water changes can affect the bacteria is if you don't remove the chlorine or chloramine the water company adds. For chlorine, either using a dechlorinator or letting the water stand overnight removes it; for chloramine you have to use a dechlorinator. Chlorine and chloramine are added to the water supply to kill bacteria, including filter bacteria. In a very mature tank the biofilm protects the bacteria form small amounts of chlorine/chloramine but in new tanks the bacteria are vulnerable. So basically, so long as you dechlorinate the new water, you can do as many water changes as you like.

How did your pH go wrong? Did you try to change it with chemicals or did it just keep changing by itself? If you tell us exactly what happened we can see how to stop this happening in the new tank. And the old one.

Using filter squeezings might help kick start the new filter's cycle, but there won't be many bacteria in the squeezings. The bacteria are tightly bound to the filter media and you really have to squeeze hard to dislodge any of the biofilm. It is better than nothing but the cycle will still take a while. What is much better is to use some of the media from the 90 litre's filter.

What you need to do is put some old media into the new filter, leaving out some new media to make room. If the new filter has carbon or a carbon sponge, that is the media to leave out. Are you intending to move all your current fish into the new tank or move some and keep others in the 90 litre?
If you move all the fish, move all the media. That contains virtually all the bacteria your current fish need. Think of the fish as being paired with the filter not the tank. This would mean the 90 litre being out of action for a while (3 or 4 months) while the new media in the new tank grows some bacteria, then you could set the 90 litre back up, transfer the old media back and get a few new fish straight away as you'd be moving ready cycled media back. You could also start adding new fish to the 175 after a couple of weeks once the tank had settled down.
If you want to split your current fish between the two tanks, just move some media over in proportion to the amount of fish you move eg if you move a quarter of the fish, move a quarter of the media. Wait a couple of weeks for both tanks to settle than add more fish slowly to both tanks.
When moving media it is quite alright to cut sponges up to make them fit. Just make sure you keep the media moist all the time between one tank and the other. It doesn't have to be soaking wet, just damp.

The most important thing to do in either scenario is to check the water daily for ammonia and nitrite, and to feed the fish on half rations for a week or so. Less food means less ammonia being excreted. If you see a reading for either ammonia or nitrite, do a water change to get it down. Transferring media means that the worst you should have is a mini cycle which will be over very quickly.
And when you add new fish to either tank, do it slowly a few fish at a time to allow the bacteria to catch up to the extra fish.

pH 7.2 to 7.4 is not low, above neutral in fact. Many people would consider it ideal for most fish.

somebody suggested bicarbonate of soda but I don't want to mess with it without knowing more about it.

A shop should test your carbonate hardness rather than buying a test kit, but get them to write down the actual number and the unit they use - hardness of both kinds use several units a bit like feet & inches, and metres & centimetres for length. You need to know which one to make sense of the numbers.

You can also use crushed coral to raise carbonate hardness.

Stop using the pH altering chemicals if you still are. They can cause pH swings.

Sorry Sue I probably confused things talking about both tanks in one blog. The old tank is 0 for everything. Just the PH problem
The new tank has a 2.0 ammonia level. It's been set up for a week now and no fish. Should I do a water change or let it cycle?

New tank - Thanks, I'll check out the cycling thread
Old tank - Do quite a few water changes. Didn't realise size of fish would affect PH. My rainbows are between 8 and 10 centimeters and I have 6. Knew they had outgrown the 90 liter which is why I bought a bigger tank. My Angels are about 6 cm each (two of them) My plec is about 12 cm and I have 3 albino cories. I know I should have them in a larger group but didn't want to get them until water problem is solved. I lost 4 corys with the water problems from over feeding.

It's not the size of the fish, it's the size of the water changes. Doing something like 10% every couple of weeks is not enough to top the KH level back up in cases where it is very low in the tap water.

About 8 years ago I came to this forum, in it's previous incarnation, to ask why my pH had dropped to 6 or below (6 is the lowest most test kits can measure). There was an advisor on this site then and he told me it was my low KH combined with me not doing enough water changes. He said I should use remineralisation salts to increase my KH but I've been doing weekly water changes without fail ever since and I've had no problems.

When you can get to the shop, take some tapwater and ask them to test it for KH. In the mean time, go to your water company's website and look for the hardness of your tapwater. It will be there somewhere, some websites make it hard to find. That will tell you what your general hardness, GH, is. If that is low, the chances are that your KH is low as well, but a test will confirm that.

This is the figure you want.

Water hardness average: 21.5mg/l calcium

This is the measure of general hardness. GH can be given in any of several units. Your water company uses mg calcium per litre. Most fishkeeping resources use either mg calcium carbonate per litre, (also known as ppm) or german degrees.
21.5mg/l Ca = 53.75 mg/l CaCO₃, or in other words 53.5ppm
21.5mg/l Ca = 3 german degrees

Those figures, 53.5ppm or 3 german degrees are what you need when you look at fish profiles on here or other sites.

Your water company classes your water as 'moderately soft' but that band is between 20 and 40 mg/l Ca, so yours is right at the 'soft' end of moderately soft.

With that GH, it is extremely likely that you also have very low KH. I suspect that this is the cause of your pH problems. KH measures carbonate, which buffers the water against pH changes. Acids are chemicals which release hydrogen ions. We measure those with pH - pH is an upside down measure, meaning that the more hydrogen ions there are, the lower the pH. Carbonate reacts with hydrogen ions turning them into water and carbon dioxide. Once the carbonate is used up, there is nothing to remove the hydrogen ions so the amount builds up and the pH falls.
If you lived somewhere like London, they have very hard water, both GH and KH. They have so much carbonate that they never see a change in their pH. I have 3 german deg KH which is why I am in danger of a pH crash, and why it happened when I didn't do enough water changes.

I suggest you get the KH of your tap water tested as soon as your shifts allow, and once we know for sure that it is low we can work from there.



The good news is that your nitrate is 4.5ppm (or mg/l). You should have no problems keeping that low in your tank. Some people have 40ppm in their tapwater and they have trouble keeping their nitrate low.