Marine tank with High Nitrates.. help?

BadCharlie

Hi, First time posting in this section.

I will give tank details.
120L juwel tank, Tetra External filter, 2 power heads, Skimmer, heater light ect.. + 20KG of live rock (kind of to much rock i think) live sand sea bed.

I bought my Marine tank 11days ago. Its a 4year old marine tank and the fish have also been in it for 4years. I had to drive to dublin and pick it up, when i turned the pump off in dublin it took me 3hours 30mins to get it home and have it all set up and pumps on ect....

Their was a good bit of hair algae on the sides of the glass + some rocks, before me getting it. Since setting it up i noticed very high Nitrates in the tank which im trying to get down. I get it down to 40 from a 20L water change but after 2 days it be back up to 80 or even a little more. In the past 11days i have mixed up maybe as much as 100L and plan on doing another 20 or 25L change today.

What i have done to try and combat high nitrates so far are.
1. I changed the in and out pipes as they looked gunked up.
2. Their was 5 snails in tank ( maybe only 2 or 3 alive when i took it) well i only found 2 in the sand and binned them as they did not look alive. If their is still another 3 in their and dead they could be casuing me problems ?
3. Lots of water changes, i either buy the water at a pet shop, or make up my own mix which has a house filter on it then i treat it before adding salt and then 24hours later add it to tank when i know temp + salt lvl's are ok. Going to be ordering a RO filter this week.
4. Changed the floss filter. Also wash it out every 3 to 4 days under tap water. Did not touch any of the other filter media but will clean then in old tank water when i do.
5. Cleaned out the skimmer machine.

What im thinking might be the cause of my problems ?
3 snails need to be found. But this will involve me taking out the stones in the tank and moving around all the sand. In doing this im once again going to be killing good stuff in the sand + i think moving around the sand will also release nitrates into the water.

Whats living in the tank are as follows.
2 clown fish
1 blue/green chromis
1 Humbug
1 boxer shrimp
+ i added 3 turbo snails to combat all the algae

All in all my self and my wife are over the moon with the tank and set up. If the person reads this message who i got the tank from Thanks very much . The kids love it also... they love the shrimp and call it a crab & have lots of fun trying to find were its hidding.

If anyone have any idea's on what i should do to take down this nitrates please tell me :P

WIZE

what media is in your filter . Is there any foam or sponge in it

BadCharlie

It's a tetra 700
It has 3 trays of tetra cf carbon filter
And on the top tray it has filter floss and one carbon filter in it. It also has some bag in the top tray with very small black plaits bits or some sort of stones in it. No idea what it has the last owner had it set up like this. He told me he removed all ceramic filter rings and bio filter balls.

BadCharlie

I cleaned out the filter totaly last night in the end. I had pulled two dead snails from the sea bed from the last owner during the day so I think I have them all.

Cleaning the filter was the only thing I could think of doing that I had not done before. It was very very dirty the more i moved down the chambers. I was reading a post about external filters on marine tanks can be a factory for nitrates if not cleaned. I was not going to clean it at all until I read that post last night. Looks like people use their filter for different reasons on marine tanks to trop.

Well I hope this works cause I'm all out of ideas.

WIZE

I got an FX5 external filter as im setting up a Marine tank
Its currently cycling at the moment .

I removed all foam and floss from the tank and filled the whole lot with Bio Balls and crushed Live rock on different levels

see what happens

BadCharlie

From the amount of reading I been doing over the past few weeks. Some people when they have live rock don't use filters at all. They will have a filter on stand by and will only use it when cleaning the tank. Well I did about a 33% change today. And did a check for nitrates and it's around 25 maybe a little lower. If its the same tomorrow I will do another 33%. I will know then if I have it under control or not.

The balls I have taking out of my tank like I said. Some people say they can cause a lot of nitrates problems. Also I'm letting my flos in and just run it under the tap every four or five days.

Good filter the fx5 my sister has one.

Senor Willy

I would bin the bio media in the external filter.
This will only produce nitrates. You can use the filter to house carbon and
to remove mechanical waster but I would wash the pads in tap water at
least once a week.

Never put crushed live rock into a filter. All it will do is soak up nutrients
and slowly realise them when it become saturated.

Instead of doing small water changes I would do one large one. This will
reduce the nitrates more than doing small changes.

When doing the rock work ensure they are plenty of gaps between them
and that there is plenty of flow over and between the rocks.

BadCharlie

Well I think I sorted the problem and I now have my nitrates between 10 and 20. It's not going back up like it was before at a fast rate.

I'm starting to clean out my filter every four days now as I'm sure that was the problem. On the bottom try under the tray you would not see the build up of crap let's call it. And I'm sure it was that, as once I moved it all. My problem went away.

Should I clean my carbon filters under tap water? At the moment I only clean my floss under the tap water and carbon filters in used tank water.

Senor Willy

Carbon filters do become biological after while.
Best to replace them after a few week or don`t bother using them at all.

BadCharlie

Update

Well my nitrates are now 0.
The big change i did was buy a second hand skimmer. After a few days my nitrates was reading 0.


So sum up what I did.
1. Installed ro unit.
2. My canister filter needed a clean badly which helped the most. If you ever finding your self moving a tank, do a filter clean the day after.
3. Installed a better skimmer, without it I don't think I could have got under 15 nitrates unless doing lots of water changes.