Constantly Cycling?????

[TheCrazyFishLady]

Wow. I learned something. I always heard it was very dangerous (for some reason) to have deep gravel. But then again, it was from a chain LFS... Good to know!

 

[mandy2936]

Wow. I learned something. I always heard it was very dangerous (for some reason) to have deep gravel. But then again, it was from a chain LFS... Good to know!

The only dangers are the chance that air would get trapped under there. After a while that trapped air turns into toxic air pockets that are bad for your fish when released in great quantity.
This is especially true with sand, because it is packed so tightly, unlike gravel. Gravel would be easier for air to escape before it turns toxic.
I'm no expert so anyone can feel free to correct/elaborate on this, however.

 

[Greenmaster]

Info on why you might not want it too deep... Click here I personally like deep substrate but it can be risky.

 

[TheCrazyFishLady]

Oh okay. I knew that could happen with sand, but never knew with gravel. I guess the LFS sales-woman was right.

 

[Greenmaster]

With gravel you have to go deeper to get the same effect as sand... it just involves water flow or more importantly oxygen concentrations. The link above just goes to another thread where me and someone else had a debate.

 

[OhNeil1969]

Just read the thread you recommended Greenmaster (My, my, my, didn't that get a little heated? Good job at taking the high road in the "debate"). It does have some very interesting info. I must add that I do have a coarse gravel substrate that allows for good gas exchange. I do have a question, however. I noticed that the thread was in a saltwater forum. Do freshwater tanks have the same concerns? I plan on using a finer substrate in strategic areas for some dwarf baby tears I'm planning on in the future and would like to make sure I don't run into the hydrogen sulfide problem. I don't plan on replacing the existing gravel but just creating pockets of fine substrate for the baby tears to take root in (think golf course with sandtraps).

 

[Greenmaster]

Basically the hydrogen sulfide producing bacteria don't care about anything except a lack of oxygen and the presence of sulfate/sulfides. I personally don't believe that H2S is that big of a deal... but you need to have proper precautions. In a fresh water tank it is more likely to be an issue because you often don't have the same agitation and turnover of the water. H2S isn't stable in water and if agitated will be released as bubbles, or at gas exchange locations like the surface of the water, or in a pump, or sump. Many freshwater setups try to minimize gas exchange in order to have higher then normal CO2 concentrations which helps the plants to grow better. Depending on the depth of the pockets of sand you wish to put in, you should be okay. But for a freshwater I would say that 1.5-2" should be max for sand pockets... unless you have high water turnover and where the water is going it gets agitated and able to release the H2S if it is produced. A sump with baffles, splashing or bubbles are good areas of gas exchange. On a side note H2S effects PH.
Your air stone and your filter are good gas exchanges. As long as the H2S is being produced slow enough then it will even precipitate out of the water...

 

[becrac16]

I always heard that for sand you always needed a kind of fish that would mix up the sand and get rid of that gas, like a loach or something.

Another filter may be in the future, but far from now. I have the money for emergencies (I have a cat and a lizard along with fish) but I'd rather spend 5 bucks on more gravel and do more water changes than 60 if I can help it.

also, sorry for offending you before. i didn't mean to come off so harsh. but far too often in the hobby, people jump into and don't realize the labor expense of having aquariums, and it's the fish who have to suffer. glad to see you are willing to take appropriate action

Thanks for that, I understand what you were trying to say and I imagine that there are many cases that people haven't done a bit of homework and want easy answers. But I was on a animal forum for a while whos members jumped on you any chance they got, so I guess I learned to be defensive!

 

[mommytron]

I always heard that for sand you always needed a kind of fish that would mix up the sand and get rid of that gas, like a loach or something.

you can get snails, too. i have MTS (malaysian trumpet snails) in both my tanks. not only do they keep the sand stirred but they are a good clean-up crew.

i've also heard of people attaching some kind of stirrer (like a chopstick) to the end of their siphon, so during PWC's they can just give the sand a little stir. i always thought this sounded like a slightly messier option, though.

 

[Tim Wheatley]

I just converted all my tanks from sand to gravel. Got tired of paying for new HOB filters when the sand ruined the mechanisms. lol The gravel still has a little of the sand underneath though just to keep bacteria basically, but now it can't be stirred. I used children's play sand and had no issues except the filters.

 

[mommytron]

I used children's play sand and had no issues except the filters.

children's play sand can be used, but i wouldn't recommend it for that exact reason. play sand is so fine that it will get sucked right up into the filter. however, you can just get a little sponge filter to put on your filter intake to prevent sand particles from flying up.

if you're set on sand, check out PFS. it looks great, it super inexpensive, and is a bigger grain of sand, so it doesn't cloud up and get sucked into filters. i vacuum mine as if it were gravel. i have no complaints about it and my filters are fine i use Quickrete PFS (bought it at Aubuchon Hardware for ~$6 for 50 lbs)

 

[Tim Wheatley]

Ah darn it. I wish I'd heard of that earlier... I literally just finished last week converting my last tank to gravel... lol I would have given it a shot... Maybe next tank.