Hi everyone.

Yeah, I know, a lot seems to be wrong with my tank lately. On the upside I haven't had any complications with any other of my fish since my ellie had to be euthanised. The trouble with my tank at the moment is the Nitrate and Acidity. I have tried to lower these by doing water changes and vacuuming the bottom of my tank but they won't budge. My Nitrate stands still at 80-100mg/L and the acidity wont go anywhere closer to neutral than 6.2-6.4. I have done 2 water changes since Sunday, each of about 10-20%, and I have vacuumed a lot of dirt from the tank in this week as well. I make sure that I do not feed too much so that there is either extremely little (one or 2 pellets) food left or none at all. I am thinking of doing a 50-75% water change to see if a larger one wont make a difference and I need to know how often I should change the carbon in my filters (I have the filters that hang on the sides of the tank 2x Dolphin H500: 220V-240V 50Mhz each on a 57 gallon tank), I have had the tank for about 6 months now. I also know that live plants might help keep the Nitrate levels under wraps but here is the problem with that: I had live plants in the tank when it was cycled and they just disintegrated (literally) within a few weeks so I am not sure what caused that or whether it will happen again - I have fake plants and ornaments in the tank and Oscar is happy with them. Any ideas on what could be causing such high Nitrate levels and such acidic water and what I can do about it ASAP? Please help me sort this out as I am due to pick up a second Oscar tomorrow afternoon (I cannot push the date on as the person wants it gone out of his tank asap) and my tank is not fit to receive it.

Thanks.

Have you checked the water coming out of your tap to see if it contains any nitrate, some tap water does. What type of nitrate test have you got? Are you actually doing the test properly? In a lot of cases with different manufacturers of nitrate tests, you got to shake the bottle for a certain amount of time, if you don't do it properly, you can get a false readings.

How big is your tank? how long after a water change are you testing the water for nitrate? If your nitrate is between 80 and 100 then it's going to take quite a large water change to bring that down. I would starts off with at least 50% and then leave it to a three hours on tasks for nitrate, see what it is doing them. It's difficult to say why your nitrate is so high, we would normally associate this with lack of tank maintenance on water changes. You say you are cleaning the tank properly, that was quite a weird one.

I don't know why you are worrying about your pH, if your pH is between 6.0 and 7.0, that's pretty much spot on if you are keeping Oscars.

Keeping plants is an art in itself. Plants need lots of light to thrive. In the tropics, there is normally 12 hours of daylight every day of the year, that is why plants thrive so well. If you want plants to thrive in your tank, you will have to leave your tank lights on for quite a long time. Also, you'd have to have quite a lot of plants before it would make a big difference to the nitrate levels.

Finally, getting another fish tomorrow isn't really going to help your cause. It would have probably been better to wait until you have sorted your nitrate problem out before you have any more fish, you'll probably find the problem will just get worse because more waste will be going into the water

you could try to do larger water changes say 25-30% every second day until your nitrates come down to an accepatable level(below 40). also check your tap water to see what the readings for nitrates are there.

as for your ph oscars are fine in a wide range of ph anywhere from 6.0-8.0 as long as it remains stable it shouldnt be a problem

Hello there! In my case, this is where I discovered that an overhead filtering system works great. When the water flows over at the overhead filtering box, nitrate evaporates and free flowing water back to the tank aerate the system adding more oxygen in it. In extreme cases, I introduce some rock salt as water softener during the cycle. For a 125 gal size tanks, I usually applied 2 tablespoon of rock salt every month. I never change my water for 18 months now. I just replenish the losses due to evaporation and wash/replace the filtering medium when necessary.

I tried to post the picture of my set-up and my oscars but find it difficult to post. It is always beyond allowable size bite