I have bad luck with Coris...

[Essjay]

I'll have to leave it for someone who knows about plants. However, I can say that I also have mainly slow growing plants and I use a liquid fertiliser with no nitrogen.


But can we just check, please - is the tank heavily or lightly stocked with fish? How much do you feed them? Do you clean the filter regularly?
A heavily stocked tank may produce so much ammonia that the plants cannot take it all up, and the filter bacteria would turn the extra ammonia into nitrate.
Uneaten food would decompose to form ammonia, which may be too much for the plants again leading to high nitrate.
The brown goo in the filter decomposes to ammonia which may be too much for the plants etc.

 

[Hokieokieamy]

I'll have to leave it for someone who knows about plants. However, I can say that I also have mainly slow growing plants and I use a liquid fertiliser with no nitrogen.


But can we just check, please - is the tank heavily or lightly stocked with fish? How much do you feed them? Do you clean the filter regularly?
A heavily stocked tank may produce so much ammonia that the plants cannot take it all up, and the filter bacteria would turn the extra ammonia into nitrate.
Uneaten food would decompose to form ammonia, which may be too much for the plants again leading to high nitrate.
The brown goo in the filter decomposes to ammonia which may be too much for the plants etc.

Since my tank is around 30 gallons, I never go above that in inches of the fish all together. I’m usually slightly under the 30 inches. I typically fish them a small pinch of flakes once a day and I give my pleco an algae tablet once a day. My filter is relatively new so I haven’t cleaned this one yet but I would usually clean my filter every 3 months.

 

[Hokieokieamy]

Another one of my fish died I’m going to try to use a nitrate remover product and see how it works. I can’t think of why else my fish would be dying...

 

[Essjay]

We know that you have zero nitrate in your tap water. We also know that your fertiliser has a small amount of nitrate (given as nitrogen on the packaging). The level of 40 ppm in your tank water just before a water change must come from somewhere, so before buying a nitrate remover we need to explore where this nitrate is coming from.

The first thing is to eliminate the fertiliser. When you add the plant fertiliser, is it one dose a week or every day? If it is one dose, that makes it easy to check. Test nitrate just before you add it, then again half an hour after adding it (to allow it to mix in). Any difference is due to the fertiliser.

If the fertiliser is not the cause, we need to look for something else.
In a heavily planted tank, nitrate should not increase. Nitrate is made in a tank by the bacteria converting ammonia from the fish into nitrite and then nitrate. Plants take up ammonia faster than the bacteria and they don't turn it into nitrate. If there are enough plants, they should take up all the ammonia so nitrate should not increase.
If there are not enough plants, then the bacteria will deal with the excess ammonia and nitrate will go up.
So the first question is, can we see a photo of the tank please so that we can judge if there are enough plants.

Then there's the fish. Fish excrete ammonia. The more fish there are, the more ammonia they make., and the more nitrate it is turned into. Overstocked tanks will create a lot of nitrate.
How many fish, and what species do you have?

Uneaten fish food will decompose to make ammonia, which gets turned into nitrate. Over feeding the fish is another cause of high nitrate.

The brown goo that collects in the filter is fish poop, uneaten food, bits of dead plant etc and these decompose to make ammonia, which gets turned into nitrate. The goo is often referred to as a nitrate factory, and should be cleaned out of the filter at least once a month, preferably every couple of weeks.
Do you clean the filter regularly, and how much of the brown goo builds up in the filter?


If we can work out where the nitrate is coming from and rectify the cause, it will be better for your fish.

 

[Hokieokieamy]

We know that you have zero nitrate in your tap water. We also know that your fertiliser has a small amount of nitrate (given as nitrogen on the packaging). The level of 40 ppm in your tank water just before a water change must come from somewhere, so before buying a nitrate remover we need to explore where this nitrate is coming from.

The first thing is to eliminate the fertiliser. When you add the plant fertiliser, is it one dose a week or every day? If it is one dose, that makes it easy to check. Test nitrate just before you add it, then again half an hour after adding it (to allow it to mix in). Any difference is due to the fertiliser.

If the fertiliser is not the cause, we need to look for something else.
In a heavily planted tank, nitrate should not increase. Nitrate is made in a tank by the bacteria converting ammonia from the fish into nitrite and then nitrate. Plants take up ammonia faster than the bacteria and they don't turn it into nitrate. If there are enough plants, they should take up all the ammonia so nitrate should not increase.
If there are not enough plants, then the bacteria will deal with the excess ammonia and nitrate will go up.
So the first question is, can we see a photo of the tank please so that we can judge if there are enough plants.

Then there's the fish. Fish excrete ammonia. The more fish there are, the more ammonia they make., and the more nitrate it is turned into. Overstocked tanks will create a lot of nitrate.
How many fish, and what species do you have?

Uneaten fish food will decompose to make ammonia, which gets turned into nitrate. Over feeding the fish is another cause of high nitrate.

The brown goo that collects in the filter is fish poop, uneaten food, bits of dead plant etc and these decompose to make ammonia, which gets turned into nitrate. The goo is often referred to as a nitrate factory, and should be cleaned out of the filter at least once a month, preferably every couple of weeks.



If we can work out where the nitrate is coming from and rectify the cause, it will be better for your fish.
Do you clean the filter regularly, and how much of the brown goo builds up in the filter?

A picture of my tank is attached. As you can see, not too many plants...I would like more though. I never go above the 1 inch per gallon in terms of how many fish to stock my tank with. I used to think I had to clean my filter every 3 months but will definitely do it every month now. I had not realized the brown goo was fish excrement. I cleaned it out last night. There wasn’t a ton of brown goo but definitely enough to turn my paper towel brown.

 

[Essjay]

How about the fertiliser? Is that added as one dose a week, or small doses every day?
Of the plants you have only the one on the right hand side is a fast growing plant so you don't need much fertiliser. I think it's an Amazon sword? These benefit from root tabs pushed into the substrate near the roots.

If you want more plants, I can recommend floating plants - something like Amazon frogbit or water sprite. These have the added benefit that they provide shade for the fish - and the gouramis would love them.

 

[Hokieokieamy]

How about the fertiliser? Is that added as one dose a week, or small doses every day?
Of the plants you have only the one on the right hand side is a fast growing plant so you don't need much fertiliser. I think it's an Amazon sword? These benefit from root tabs pushed into the substrate near the roots.

If you want more plants, I can recommend floating plants - something like Amazon frogbit or water sprite. These have the added benefit that they provide shade for the fish - and the gouramis would love them.

I used to do the fertilizer once a week but now I am too scared to and may do it once a month, of a much smaller dose than called for. Also, I forgot to mention this but last night, I checked the nitrate levels in my tap water and it was 5-10ppm and not 0 like I said earlier. I don’t think I waited long enough last time when I checked it.

As for the plants, I do have tabs but was told on here that the liquid should be good since I have multiple plants that could benefit from it as well. I love your suggestions on the plants. I will definitely look into those

 

[Essjay]

Your tap nitrate is not terribly high.

Try the floating plants and see of they help. If they don't we'll have to thing again.