Cotton Like substance on gravel

Hello Im new to the site and to aquariums.
I like the hobby, however have a 120 gallon tank that I can not stabalize. The PH is low, the ammonia is high, and a cotton like substance seems to be growing on the gravel. Fish are dieing pretty often, any advice?

Welcome to our forum. From your description, it seems like the aquarium may not have been cycled. It has to do with nitrogen and beneficial bacteria, all of which is discussed in other posts and blogs on this website. When a tank is not cycled, it will have ammonia spikes that are deadly to fish. The cure-all is a series of 20 or 30 percent partial water changes (every day for a week) followed by weekly partial water changes. That removes toxins like ammonia. A 120 gallon aquarium, which most of us would love to have, may require six or eight weeks to cycle. The daily water changes MAY save the fish that are left. A few things that will speed the cycle are some gravel or decorations from an established aquarium and floating plants like water sprite and hornwort. Also make sure to not over feed, and do a little research on the fish in your aquarium. Some require different water conditions, and many are not compatible.

Maybe that will give you a start. Ask plenty of questions, and we'll help.

Welcome to the forum!

How long have you had your tank set up? Did you add fish to it as soon as you got it up and running?

I agree with John, and just a little reading through older posts and blogs will explain the nitrogen cycle in detail.

The cotton stuff on your gravel is probably fungused uneaten food. This needs to be syphoned out immediately. It will increase your ammonia and mess up your tank bad.

The key to uneaten food is to feed no more than what the fish can completely consume in 2-3 minutes.

If this is new tank syndrome and you're having nitrogen cycle issues... If it was me... I'd vacuum the gravel with a syphon. Taking out as much water as possible. And put in fresh water treated with Bio Spira - Or some other instant cycling treatment, and check to see if that includes the water conditioner... If it doesn't remove the chlorine, you'll need Chlor Out, or Amquel Plus... Stress Coat or something like that.

What fish do you have in your tank now?

I know this is long winded, but with a few answers to our questions... Perhaps we can give you a hand learning about your tank.

had the tank for six months. have severens, firemouth, parrots, leopurus, bala sharks, gouramis....semi-agressive, largest fish is gold severen - about 6 inches.
all gravel has been removed and undergravel filters been removed, since the fungus was everywhere, even under filters and in tubes that were upright....pumping lots of air in tank....

i feed very little, since I ve read not to over feed them.

I just bought a complete test kit and it is stating that Nitrates are off the chart - DANGEROUS zone. says change 25% of water and add bacteria, Do you agree?

Thank you for your responses,

6 months? Wow... Usually we hear things like this in the first month or two.

If you don't overfeed... the fungus is odd... Especially if it was under the undergravel filter.

Did you thoroughly rinse the gravel and the undergravel filter before putting it in the aquarium?

The only other thing I can think of is that there isn't enough water flow at the bottom level of the tank.

Is it a Long? Or a Tall tank?

If it is a water flow issue, perhaps some bottom feeders would help... As in moving the gravel around on the bottom of the tank... If you got a group of 10 or so, they'll stay busy and perhaps help to keep the fungus from forming.

Maybe there's some other members that might have more suggestions.

I know you can get a power head (called something or another) that will move the water on the bottom of the aquarium.

As far as the water changes... If you usually do weekly water changes of 20% or so, you could probably get away with a larger water change, maybe 40% or so. If you only do monthly water changes then I'd do 20%. Then I'd do 20% every couple of days, for a week or two.

If your tank has been running for 6 months... you should have some bacteria built up... in the filter media at least. However pulling all the gravel... I'd add some bacteria... Do you have another tank? You could take some containers of gravel out of the established tank and set it in the big tank, but it'd take a lot of gravel to pull that off.

I like undergravel filters personally. I know that John does too. I'd rinse them really really well... Maybe with a bleach solution, then rinse them again really well, and put them back in.

Good Luck!

Most of the beneficial bacteria live in the filter media and the gravel, so you're pretty much restarting the nitrogen cycle process. Many people have healthy aquariums with no gravel or other substrate; my own preference is a gravel substrate and live plants. In addition to what Angela had to say, I'll note that several, live bacteria products are now available to help with the nitrogen cycle. It will still take some time, and you may still have to compensate for the buildup of ammonia.

So far as gravel cleaning, you don't really have to take it out of the aquarium. A syphon with a large diameter uptake tube will clean the gravel without removing it. You can even buy maintenance systems that do the syphoning as well as the refill. Most recommend cleaning only half the gravel during scheduled water changes. Certainly you should syphon out all the gunk, but leaving some of the gravel substrate untouched for a week will help maintain the colony of beneficial bacteria.

Please keep us updated.