How Much Substrate?

[oakes]

hi, i am considering changing from gravel to sand in a tank that has a base 90cm long x 60cm wide.
I would like a substrate thickness of about 2.5cm.
How do i determine how much sand i will need?
I have a 20kg bag, but i don't know if it will be enough. I don't want to get halfway through the process only to realise that i need to buy more.

 

[Pleccy]

Go to www.practicalfishkeeping.co.uk and click tools, scroll down and there is an aquarium substrate calculator. Simply type in the dimensions of your tank, along with the type of substrate and the depth you want, and it will calculate how much you need.

 

[jonnyf84]

i did this a few months ago, you'l need slightly more than that 25-30KG for 2-3 inches. don't go over 3 inches.

 

[oakes]

Excellent, thanks.

btw the range of calculators on that website is amazing.

 

[Spishkey]

is there a downside to having too much substrate? i have sand which in places is 4 to 5 inches thick. and no mess than 3 inches in the other places. is this bad??

 

[Miss Wiggle]

you're reducing the volume of water in the tank! there's no need to go more than 3" unless you've some specific planting substrate that requires it so if you put more in then all you're doing is reducing the capacity of your tank meaning less fish or the same amount of fish but less of a safety net in the volume of water to dilue toxicants!

 

[Pleccy]

A sand depth of over 1-11/2" is asking for trouble, as it will begin to turn anaerobic and produce foul-smelling hydrogen sulphide gas, which can even kill fish.

 

[Miss Wiggle]

A sand depth of over 1-11/2" is asking for trouble, as it will begin to turn anaerobic and produce foul-smelling hydrogen sulphide gas, which can even kill fish.

don't mean to come across as confrontational pleccy, but this is one of those fishkeeping rumours that winds me up. not one single person on this forum has actually managed to produce a shread of evidence to support this, not even any anecdotal evidence of it happening to them. I've not yet met a fishkeeper who said they experienced one of these gas bubbles killing their fish. yes a poorly maintained substrate will go manky, but the depth of the substrate alone will not make it go anerobic!

I simply do not believe that this is true, but as ever I'm happy to be corrected so if you've seen some evidence that the rest of us haven't then please do share it with us!!

 

[Pleccy]

Let's just say that if you have a deep layer of sand, that hasn't been touched for several months, it will begin to compact and stagnate. Have you ever removed a piece of bogwood that has been sat on top of a sand substrate for a long period of time? When you remove it it will release air pockets which contain hydrogen sulphide gas which is formed when organic matter (e.g faeces) breaks down and mixes with the air in these pockets. The same applies to a sand substrate. If you go to the Practical fishkeeping forum many other forum member on there will say the same thing.

I've seen this several times and boy does it stink!

 

[Straydum]

there was this debate on the air pockets issue at the scientific section and i think they agreed it wouldn't happen or is not very likely. bottom line is as long as your sand isnt too deep and is stirred every now and then it should be fine

 

[Spishkey]

strangl enough my water has been smelling foul lately and no amount of water changes has cleared it.
the sand is ruffeled up every week though to get rid of the algae growth round the sides. i have it so deep because a) i have a lot of plants which i need to plant deep to stop the angels pulling them up and b) for my banjo catfish and kuhlis to go burying in.

methinks i need to get some sand out of there now though.........?

 

[Pleccy]

there was this debate on the air pockets issue at the scientific section and i think they agreed it wouldn't happen or is not very likely. bottom line is as long as your sand isnt too deep and is stirred every now and then it should be fine

If you stir the substrate every week or so then compaction shouldn't be a problem, it only applies to people who don't do it. However if you have live plants then a deep substrate will be no problem as the spreading of roots will disturb the substrate.

 

[aaronnorth]

Tom Barr had his substrate 12" deep!!!

when the hydrogen sulfide is released into the water, it is quickly reacted with the oxygen in the water and become harmless,

H2S + O2 > H20 + SO

 

[Pleccy]

Tom Barr had his substrate 12" deep!!!

when the hydrogen sulfide is released into the water, it is quickly reacted with the oxygen in the water and become harmless,

H2S + O2 > H20 + SO

Considering the amount of photosynthesis going on in his tank I can imagine it being quite harmless, however in tanks with no plants and a deep substrate of sand hydrogen sulphide can quite easily build up.