Crushed Coral Media Bag in Fluval 207 Cannister?

[Eric G]

Hi, I am trying to findout if it is ok to place a crushed coral media bag in my second tray with my bio rings in my fluval 207 canister? I just tested my KH and GH, KH is at 53.4 ppm and my GH is at 178 ppm. My PH is looks to be between 7.0 and 7.2. I am running a fresh water 30 gallon tank, molly's, platies, few algae eaters and a couple snails, also some plants ( java fern, water sprite, momeywort, anubias, scarlet temple). I want to raise my PH and KH a little. Appreciate any suggestions.

[Theplatymaster]

@Eric Gshould be fine.

On 3/9/2023 at 5:58 PM, Eric G said:

few algae eaters

 what kinds of algae eaters?

[Guppysnail]

I use the 07 series canisters. Yes it is fine but I think you get more bang for the buck to add it to substrate if you don’t mind seeing it. 

[Eric G]

On 3/9/2023 at 6:01 PM, Theplatymaster said:

@Eric Gshould be fine.

 what kinds of algae eaters?

Flying fox and Siamese 

[nabokovfan87]

Yes it would be fine. Treat it as a chemical media in the filtration chain.

Mechanical --> Biological --> Chemical

[Eric G]

So I have had the Crushed Coral Media bag above the bio rings for about a week now. My PH is now around 7.2 to 7.4, haven't seen a difference in KH yet, will check again tomorrow. How long should I keep the media bag in the filter? I do not want the PH to get to high and stress out the fish or plants.

[nabokovfan87]

On 3/16/2023 at 3:51 PM, Eric G said:

So I have had the Crushed Coral Media bag above the bio rings for about a week now. My PH is now around 7.2 to 7.4, haven't seen a difference in KH yet, will check again tomorrow. How long should I keep the media bag in the filter? I do not want the PH to get to high and stress out the fish or plants.

It would be in there long term.  As you change water out week to week that is how you would modify the PH.

The coral should generally keep it stable.  You might already have buffered the water to the level per the amount of CC you have in the tank.

[TeeJay]

I have zero kh out of the tap but pretty hard gh. So I like to mix the cc into my gravel as well as the main way to raise the kh. Then a small amount in a media bag in my filters. Since you will be doing regular water changes your always going to be taking out some of the kh in the tank in that process. It's not really a oh it raises it to where I want it so now I don't need it anymore type deal. In my 29 gal I have about 3lbs mixed with the gravel and about .5lbs media bag in the filter.

That keeps my kh at a steady 6 degrees. The nice thing about it is that once it gets to a good level the rate that it dissolves slows down.

[DeadStang]

On 3/16/2023 at 6:25 PM, TeeJay said:

I have zero kh out of the tap but pretty hard gh. So I like to mix the cc into my gravel as well as the main way to raise the kh. Then a small amount in a media bag in my filters. Since you will be doing regular water changes your always going to be taking out some of the kh in the tank in that process. It's not really a oh it raises it to where I want it so now I don't need it anymore type deal. In my 29 gal I have about 3lbs mixed with the gravel and about .5lbs media bag in the filter.

That keeps my kh at a steady 6 degrees. The nice thing about it is that once it gets to a good level the rate that it dissolves slows down.

I like this. I have been considering adding the CC to the gravel (it will blend in well) as I currently just have a bag of CC in my HOB above the biorings and my KH has actually decreased over the past couple of months due to well water/seasonal fluctuations.

[Eric G]

On 3/16/2023 at 8:19 PM, Pepere said:

If it was me I wouldnt be using crushed coral.

You already have 10 degrees of GH and dont need to raise it any more for plants, though your Mollies might appreciate a few degrees higher though I kept them nicely with very low GH in the 80s.

I would be using some sort of Alkalinity buffer.  1 1/2 teaspoons of  Seachems Alkalinity buffer will raise the kh by 2.8 degrees in 30 gallons of water.  That would put you close to 6 degrees kh.

Makes sense, I noticed after a week using the crushed coral that the pH went up , but no difference in KH. I read that crushed coral will help raise pH levels but slow levels if any in KH and GH... if that is true. I removed the media bag today. I will try the Alkalinity buffer that you recommend to raise the KH. Can using limestone rock have the same effect? Or would the Alkaline Buffer give me better control of raising it to the parameters I require?