Best way to get Nitrates down

[jason19]

Hi all,

Ever since my tank has cycled and I added fish, my water quality has shown as follows:

pH 7.2-7.6
Ammonia - 0
Nitrites - 0
Nitrates - 40-80ppm

I have watched a few videos and done 25% water changes but it seems to have had little impact on the nitrates. I know anything above 40ppm can cause toxicity to fish so I am trying to get this under control. I have read plants help with nitrogen however I don't think my substrate is suitable as it's just pebbles, I read plants sometimes need fertiliser soil.

Is there anything else I can try to get the nitrate levels under 40ppm?

Thanks.

[colinquilliam1]

Food and waste is going to fall between the pebbles and rot down. Fish and plants can't do much with it because they can't get to it. You'd be much better using a different substrate underneath. Then instead of covering the entire bottom with pebbles, place them in clusters so you can still clean the bottom during wc. Otherwise its a continuous battle

[Aiken Drum]

The best ways to keep nitrates down.

- Dont overstock.
- Dont overfeed.
- Water changes.

A planted tank will help as well. There are plants that dont need specialised substrate or much light like java fern, java moss, anubias. These dont even need to be planted in the substrate. Just tie or glue (cyanoacrylate) the plant rhyzome to a piece of rock or driftwood to weigh it down.

I would recommend doing a couple of back to back biggish water changes. Say 50% then another 50% the following day. Try to get nitatres down to around 10ppm. If after back to back water changes your nitrates arent coming down significantly, something else is going on.

The process then should be 30% weekly water change. If following the water change you are down to around 10ppm nitrate or lower, great. Stick to 30% per week.

If following 30% water change you are higher than 10ppm then either increase to 50% weekly or 30% twice weekly. If this still isnt getting down to around 10ppm or lower, you are probably overstocked. Look at rehoming some fish or get a bigger aquarium.

The comment about your pebble substrate is valid also. If there are large voids then waste food will get in there and decompose adding to the bioload on the filtration system.

[Ulrichsd]

Check your tap waster for nitrates. Some tap water has nitrates

Assuming it is low, do 50% water changes weekly and vacuum the substrate with a python water changer.

[Aiken Drum]

Originally Posted by Ulrichsd

Check your tap waster for nitrates. Some tap water has nitrates

Assuming it is low, do 50% water changes weekly and vacuum the substrate with a python water changer.

Checking tap water is a good idea, but nothing amiss showed up while we was doing the fishless cycle. However a python is a bit of an overkill for a 40 litre tank (we have been dealing with his cycle last few weeks so i know his tank).

[Ulrichsd]

Originally Posted by Aiken Drum

Checking tap water is a good idea, but nothing amiss showed up while we was doing the fishless cycle. However a python is a bit of an overkill for a 40 litre tank (we have been dealing with his cycle last few weeks so i know his tank).

Sounds like bigger (50%) and more frequent water changes are just what the doctor ordered

[ZxC]

More plants.
More water changed at a time.
More removal of organics before they have a chance of partaking in the nitrogen cycle.

[jason19]

Thanks all for the replies. I have a substrate cleaner on the way and should be here in the next few days so I'll definitely try this and see if it works.

Regarding the change of substrate, what would people be recommending? Plain sand? It is plausible that the food/biomass waste could be getting trapped in the pebbles. I have been using frozen bloodworms which very few seen to hit the bottom so don't think overfeeding is an issue. There are currently only 4 fish in the 10g tank as well so don't think overstocking is the problem.

I'll try cleaning the substrate along with bigger water changes. Failing that, I'll replace the substrate.

Thank you all.

[jason19]

UPDATE - Did a 50% water change today and that has dramatically helped. Nitrates before were around 40ppm-80ppm and now seem to be somewhere between 10ppm-20ppm. Still await substrate vacumn to come so that should also act as a preventative measure i'm sure.