# To clean substrate?



## xev11 (Feb 18, 2010)

I have eco complete gravel which is about 3 years old now. I have almost never vacuumed it. I have read and was told that it collects foods and whatever else; it decomposes, and becomes nutrients for the plants. I have also read that the area becomes a home to many types of bacteria that are generally good for the tank. However the level of the mulm has reached to be within a half inch to the top of the substrate. 
I also am overstocked with guppies. So the nitrates are high. Whenever I do 20-30% water changes (the max I can do without lowering the water below the breeder net and also have enough replacement water), the nitrates barely change. The nitrates aren’t a problem to the current inhabitants (no abnormal deaths), but I do understand that it is far from an ideal environment for all my fish. 
This has lead to me to think that the mulm may be a cause of the high nitrates (in addition to being overstocked). Would it be wise to clean the top inch or so of the gravel that is currently unplanted? If so, I would also do a 30% WC to get rid of any particles that get into the water column. 
Would this have a chance at decreasing my nitrate level and not disrupt any good bacteria colonies/whatever else that is good in the substrate?

What other info should I provide to help you guys in helping me?


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## Darkcobra (Nov 23, 2009)

I also overstock guppies.

Some mulm accumulation in the substrate is a valuable nutrient source for plants, but when it consistently accumulates faster than it can be consumed, you eventually have to step in. Otherwise it seems to choke off circulation in the substrate, and I notice a decline in the health of plants; especially those that are root-dependent.

So vacuum away. You can do a occasional heavy cleaning. Or frequent lighter cleanings. Whichever you prefer. Only if you do heavy cleanings frequently do you risk making it "too clean" in our situation.

In some spots vacuuming isn't possible because plants are in the way. That's ok, but sometimes that's pretty much the entire tank. In which case I vacuum what little I can, and use a DIY "liquid gravel vac" method for the rest.

Measure out 2 tbsp. of 3% H2O2 per 10G of tank. Dilute 15X with water, the exact amount isn't critical, so I just eyeball this part. Use a syringe with a long blunt needle and inject into the bottom of the substrate in a grid, 2" apart, about 1 tbsp. per location. You'll probably run out before you do the whole tank, that's ok.

A day later, do a water change. Then if needed, mix more solution and continue treating parts you weren't able to the first time. Repeat until complete.

The H2O2 helps break down some mulm immediately. It probably destroys some beneficial bacteria as well, but they seem to rebound with new vigor; watching the process through the front glass, some more mulm disappears over the next week. Plants don't seem to be injured, they will often experience a growth surge.

After a week, if it doesn't look clean enough, I repeat the process once more. And then I'm set for the next six months to a year.

There are commercial "liquid gravel vac" products as well, which I think you just dump in the tank. They seem to get good reviews, but I haven't personally tried them.

While all this is good tank husbandry, you make be disappointed to find your water nitrate level doesn't decrease as much as you might expect. Which makes sense if you think about it, the reason that mulm is accumulating is because it's _not_ breaking down at a substantial rate.


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## xev11 (Feb 18, 2010)

Thanks for the tip about the liquid cleaner. Did you come up with it yourself or found it somewhere? After a quick search i wasnt able to find any mention of it in an aquarium, just for cleaning medical and scientific equipment. 

I do know about hydrogen peroxide used to kill algae.


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## Darkcobra (Nov 23, 2009)

I saw a post a long time ago where someone had a spot in their substrate that was too deep/dirty, had gone anaerobic, and was producing toxic hydrogen sulfide gas. They thought adding oxygen via H2O2 might allow aerobic bacteria to reestablish and compete. Don't recall any other details, or whether it was actually tried and results were posted.

But the idea stuck in my head, in case I ever faced that issue. Some time later I had some ugly mulmy spots against the front glass, that couldn't be vacuumed because plants were in the way. They looked like they could potentially go anaerobic if they weren't eventually dealt with. Which made me remember the idea. I wondered if it might produce some positive effect even at this stage, so I started playing with it, with success.

One caveat I forgot to mention. If you have Marimo balls, remove them prior to treatment. They trap H2O2 leaking out of the substrate and their bottom will burn. Seems logical in hindsight since they're algae, but given their high H2O2 resistance and the dilution, I didn't expect this until I actually damaged one. No other plant I've kept has been affected. But I haven't kept them all. If you have a dense substrate cover of something known to be H2O2 sensitive, a limited test is suggested. Riccia carpet comes to mind as a possible example.


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## xev11 (Feb 18, 2010)

Thanks for that info. I dont have a marimo in this tank but Ill remove my floating riccia just in case. I'll try it in a small spot to see what happens.


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## Newt (Apr 1, 2004)

Malaysian Trumpet Snails


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## Diana K (Dec 20, 2007)

To reduce the nitrate:

1) Vacuum the visible mulm. 1/2" deep is way too much. 
2) Feed less. Skip one day a week, and the rest of the time try 25% less at each meal, even 50% less. 
3) Improve the conditions for the plants you have. 
a) Supply missing nutrients starting with carbon.
b) increase the light. 
4) Add more plants, especially plants that grow out of the water. With their leaves in the air they get their carbon that way, and the roots in the tank will remove a lot more N because the plants are not C limited. 
5) Do more frequent water changes. If you can only do 20% max, then try doing that much twice a day for a while.


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## xev11 (Feb 18, 2010)

Thank you

1. Did in the areas i could reach. Will continue doing weekly. 
2. Understood. Although I feel i already feed little as some fish have slim stomachs
3. Dosing Seachem Ferts for now. (Have dry available for later). I have a Finnex Planted+ over the 16G for about 8 hrs. If I increase duration, wouldn't that exacerbate any deficiency (i have low phosphate, possibly low potassium) -- especially if doing frequent water changes?
4. I have many regular hygro stems growing out of my breeder net. Their roots are very strong. I also let anything that breaches the water, grow out. 
5. If I do very frequent water changes, how do I fertilize the plants properly? I assume dose very lightly while doing the frequent changes then increase when doing the EI type schedule (but not with those proportions).


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