Nitrates - What would you do???

[Margueritte]

Hi !

We had run out of test kits and managed to get again last Thursday 3 Feb.. Much to our amazement when we tested for nitrates, we discovered that we had a reading of over 40 ppm, normally run at 0-5 ppm. The water immediately got changed – 120 litres (tank size 380 litres) tested again the following morning…. Still over 40 ppm… did water change again on Saturday 120 litres…. Checked this morning… nitrates still over 40 ppm. Did another water change this afternoon, this time 220 litres…. Checked nitrates 1 hour later…. Still over 40 ppm. We have cleaned every single surface in the tank, checked live rock.. all fish present… all crustaceans present… There is no algae bloom in the tank….Please make some suggestion as to what the problem can be…I can’t think of anything else to do..

Thanks
Margueritte

 

[Anonymous]

Over 40 ppm is pretty darn high, how long has that tank been set up? What kind of setup is it?

Are you sure of your result, not a decimal in the wrong spot or something? Not trying to insult your intelligence or anything, just clearing the underbrush... :wink:

BTW, welcome to RDO Margueritte. How is the summer weather in Cape Town?

 

[Margueritte]

Hello Brian

Thank you for answering!!! The weather is absolutely stunning this time of year, not that we complain... I have been very meticulous in doing my testing, I realise that a mistake can be made very quickly..


We are very fortunate to live off a beautiful Indian Ocean Coastline. We have an aquariam called "The 2 Oceans" approx 40 kms from our home, we are members of the Aquariam and therefore get filtered sea water from them.

I have since done all the tests again !!

Phosphates - 0
DKH - 10
SG 1.025
Temp 25
PH - 8.3
and finally Nitrates - dropped to 20 ppm.

I did water checks on the sea water before I put it into my tank. No Nitrates !!

 

[ChrisRD]

Hi and :welcome:

We can probably offer more helpful responses if you describe the system, filtration, stocking levels, etc. a little more.

 

[Margueritte]

Hello Chris

Thank you for the warm welcome.

My Tank is 385 litres (I dont know the equivalent in US Gallons) and has been operational since June 2004. The equipment is as follows : 1x Berlin air skimmer, 1x pump + air skimmer, 2x 3200 LPH circulation pumps, 1x UV, 1x AquaClear 500 consisting of Carbon, Stinted glass (I think that is its name?), 1x Aquaclear 200 consisting of crush live rock.

The inhabitants are 1xyellow tang, 1xregal tang, 2xskunk clowns, 2xcommon clowns, 2xcleaner wrasse, 2x engineer fish, 1x candy goby and 1x yellow-tailed damsel. 3 cleaner shrimp and 1 boxer shrimp.

No substrate. 10 kg live branch rock.

I must confess I have a passion for anemones and are guilty of having 4 small ones namely 1x fluorscent green bta, 1x florscent pink bta, 1x h.magnifica (her name is Annie and she rules the tank, very happy never moves from her rock) and 1 Malu.

Lights are 3xwhite fluorscent and 2 blue acrinic. Afternoon sunlight falls into the tank during summer and everybody loves it!!.

Hope this info helps!!
Thanks for your help
Margueritte

 

[ChrisRD]

IMO there are a few things that could be contributing to the nitrate problem. The first and most obvious to me is the live rock. You don't have much live rock in the tank and this is what's going to provide the denitrification. Adding some well cured live rock, and/or live sand will provide you with some much needed denitriciation.

Also, a better skimmer can help (indirectly) with nitrate control by removing more wastes from the water column before they have a chance to accumulate and get converted to nitrates by the resident aerobic bacteria. Not sure how large or effective your skimmer is, but that could be something that's contributing too.

One final thing - the filters, especially the one filled with crushed rock. They need to be cleaned frequently (say weekly) or they'll likely accumulate detritus which will in-turn break down and ultimately be converted to nitrate by bacteria. In fact, if you have a good enough skimmer and plenty of live rock/live sand you really don't need fulltime mechanical filtration. Many choose to utilize no, weak, or only periodic mechanical filtration under those circumstances (adequate skimmer and live rock/sand) as it's generally a lower maintenance approach. BTW, those hang-on type filters are handy for periodically polishing the water or running some activated carbon though, even if you're not using them all the time.

If you're not already doing it, take the opportunity to syphon out any visible detritus when you do water changes. Getting this stuff out of the system before it can decompose will help.

BTW there's about 3.785 liters per US gallon, so your tank is about 102 US gallons.

HTH

 

[ChrisRD]

BTW, how long have you had the anemones? IMO you don't have sufficient lighting to keep them alive long-term.

 

[danmhippo]

Has anything been missing or dying in your tank just prior to the elevated level of nitrate?

Since you do not have any means of denitrification in your tank, as soon as you feed more, everything you feed to your tank will pretty soon turned into nitrate. There are several methods of denitrification, such as Deep sand bed setup or denitrifying canister that help create environment for denitrifying bacteria to colonize and populate. I think Aquamedic has a denitrifying unit. Or search the net to see if there are other options to suit your need.

Driving 50km one way seems a bit far for me just to get saltwater. But since it's free...........

 

[Margueritte]

Hello

My apologies for taking so long to get back to you!! I think we are on different time zones.

Chris
I should have been more descriptive with my lights, they are 1.2 metre florescent tubes with a 18000 Kelvin rating, 30 watts. (4x white, 2x blue)
At the moment, till the money situation gets better, I am running 2 different skimmers on my tank, namely 1 Berlin Air Skimmers (rated for 350 litres) and 1 with a pump / air filter combination, (dont know the rating). They are very active and seem to do their work well..
My tank gets quite a lot of sun (approx 3-4 hours) every afternoon.

Thank you for the info regarding denitrifying canisters. I am trying to achieve this by utilising pieces of live rock / crushed live rock in the Aquaclear 200 canister... there is nothing else in the canister.. What do you think of this idea??? Do you think it will work?? If it does work, I am going to convert the other one which is an Aquaclear 500.

Every single surface, rock, etc has been cleaned twice in the last week!!.

Did nitrate test this morning... still sitting at 20 ppm. (I think this is the correct terminolgy.. we use Sera testing kits.. it is the best we can get here?? unfortunately we are not lucky enough to live in a country that has internet companies down the road...)

My anemones have been residing with me for approximately 6 months (I know I started early!!). They seem to be very healthy, eat a lot and to date have not moved from their respective rocks.. I organised a rock overhang for each of the anemones (not live rock but local beach rock... probably the same).

We have moved all the rocks out of the tank, caused a storm in a bucket and replaced them into the tank.. there does not seem to be anything dead..

When water changes are done, all the fish seem to realise new sea water is arriving and go crazy, they love the fresh sea water.. this makes up for the fact that we drive 40km to fetch sea water. I also do a lot of work near the aquariam which also makes this trip easier. You will laugh, we collect our RO water from the other side of the city, which is further than the Aquariam. We do not have any fish shops near to where we live, so everytime a fish is bought, we travel!!!!

Hope this answers all your questions!!!


Thanks
Margueritte

 

[ChrisRD]

IME you're going to have much better luck with denitrification if you put the live rock and/or live sand directly in the main tank. I'd suggest large pieces of live rock with an open rockscape. Tight piles of smaller pieces and/or rubble tend to accumulate detritus. If you use live sand (I prefer no sand, but some like the look or have animals that require it for habitat), plan on getting some critters in there that will help keep the bed stirred and cleaned for you (burrowing snails, cukes, etc.). It's important to not let detritus accumulate in the bed. If you do some searches on the board I think you'll find a lot of information about these topics here at RDO.

As for putting crushed rock in hang-on filters, IMO it's part of the problem, not really a solution. IMO it's not going to provide much denitrification as you won't have much rock in there, and flow rates are relatively high. This setup is more efficient at trapping detritus and hosting aerobic bacteria (ie. providing additional nitrification, not denitrification) - neither of which is helping you. Without very frequent cleaning (maintenance headache IMO) the accumulated detritus will quickly start to decompose and ADD to your nitrate problem.

HTH

 

[starfish 1]

Yes you need more cured live rock for a stable tank. I also think you have a heavy bioload with 12 fish and anemones in a not quite a 100 gallon tank. Good luck, hope you get the water right soon.