Australian Red Claw High Nitrates and Nitrites

[ScubaTron]

Hi,

I am new to this forum, but it looked like the perfect place to hopefully get the help that I need. I also hope that I am posting in the correct place with relevant information as I'm not a big forum writer but possibly will write more now that I have the time.

I currently have a large lobster setup that I wish to hopefully turn into a breeding setup in Malaysia. I have about 40 Australian red claw crayfish and they have been in the tank now for just over 1 month. At first I have a few fatalities (from not cycling the tank long enough). But it's now been almost 2 months that the tank has been running and I just can't seem to get the nitrates or nitrites under control. The volume is about 300 liters with 3 sections. The main large section where most of the crayfish are has 1 pump going directly into a pressurised canister filter that I made. There is also another pump running alone for water flow (and to stop mosquito's breeding). The top section is the main box filter that has bio balls in the bottom, then sponge medium and coral fragments followed with sponge on the top. I have also been using some probiotics to encourage nitrifying bacteria to start. The middle section has 4 females (about 4 inches each) and 1 male (about 3 inches). I have 2 fairly good size pieces of driftwood in there too. My pH is at 7.8 (trying to get this down a little bit too).

 

 

Any suggestions would be much appreciated on how I can lower my nitrites and nitrates.

Edited September 12, 2016 by ScubaTron

[jayc]

Welcome to SKF !! 

 

Hmm, the water might need to be in longer contact with the biological filter media before flowing down to the next level. 

looking at photos 2 & 3, it seems like the water from the bottom tub doesn't flow through much of the media before exiting to the next tub down. 

47 minutes ago, ScubaTron said:

The top section is the main box filter that has bio balls in the bottom, then sponge medium and coral fragments

What sort of bio balls do you use? Those plastic ones?

There are a much better bio media around. You need more surface area for beneficial bacteria. Bakki Rods or Cermedia Marine Pure Spheres or Plate blocks would be perfect for your setup.

 

So more surface area for BB, and more water flow through the bio media. Maybe block off the top tub's outlet to reduce the flow down to the middle tub, so at least half the tub is submerged under water. Think of a canister filter... the media is in contact with a lot more water, for a much longer time.

 

More plants will also help with nitrates. LOL, those plastic ones you have ain't doing shyte.

Edited September 12, 2016 by jayc

[ScubaTron]

4 minutes ago, jayc said:

looking at photos 2 & 3, it seems like the water from the bottom tub doesn't flow through much of the media before exiting to the next tub down. 

What sort of bio balls do you use? Those plastic ones?

There are a much better bio media around. You need more surface area for beneficial bacteria. Bakki Rods or Cermedia Marine Pure Spheres or Plate blocks would be perfect for your setup.

So more surface area for BB, and more water flow through the bio media. Maybe block off the top tub's outlet to reduce the flow down to the middle tub, so at least half the tub is submerged under water. Think of a canister filter... the media is in contact with a lot more water, for a much longer time.

More plants will also help with nitrates. LOL, those plastic ones you have ain't doing shyte.

Hi jayc,

Thanks for the info and suggestions. I will give them a go for sure. The bio balls I currently have are those cheap plastic round ones, so I will hunt around for something a bit better with more surface area for the BB. I will also reduce the flow from the top tub so that it fills up more so the media is in contact with the water for a long period of time and submerged more.

Hahaha. Yeah..those plastic plants cost less than 50c each, so just got them for decoration and something for the crayfish to climb on. I'll get some proper water plants and add them too.

Thanks again for the help. Appreciate it.