sand or gravel bed?

[marcoz]

ok, let's open a debate! pro and cons of sand and gravel substrates please :twisted:

[Tetley]

Hi,

Only had experience of sand - but would have thought that gravel would be a dirt trap ?? but having said that as said no experience.

Ian

[total*clowns]

We have coral sand too, nice and easy for the old goby to do his biz then !!

[flying Jock]

Hi

Gravel would be too big (partice wise) and would end up trapping detritus and eventually give you high readings of nitrates.

If you are setting up a sandbed (grain size) is paramount.

Too big and you will not be able to allow microfauna to move around the grains which will cause compacting in areas and high nitrates.

I found this out when setting up my 1st DSB :cry:

Cheers

FJ

[Simon]

Yeah I agree with FJ on this one. :Thinking: Gravel is too big and would attract yuk more quickly. I've got coral sand and lots of shells which keeps my hermits and sand sifter busy! :-D

[Macca]

Can of worm being open here but here are my opinions.

If you want nitrate reduction then use a very fine sugar sand (mud like). Make sure it is natural not silica. Make it at least 3 inch deep. Do not disturb.

If you want critters then the sand is to finr and you may want to set up an are for pods to accumulate. I use a dark cryptic area for this filled with live rock rubble.

I agree (IMHO) If the grain size is too large then this is just a trap for deterius(sp) to gather causying all sorts of problems.

James

[Dons1903]

I have cleaned out a fair few freshwater tanks with gravel to realise how much detritus gathers between the stones... euck!!!

Sand is the way 8-)

[Buster]

Well here you go. I have very fine live sand in my AR620 with no problems upto now. but in my larger tank I have no sand or crushed coral or gravel again upto now no problems :whistling:

I also believe as stated it all depends on what you want to keep, there are lots of pros and a lot of cons. it will be interesting to see how this thread progresses.

[marcoz]

If you want critters then the sand is to finr and you may want to set up an are for pods to accumulate. I use a dark cryptic area for this filled with live rock rubble.

can you elaborate? please bear with me - only got my tank in June(so much to learn about!) :?

[marcoz]

I bought a mature tank with gravel already in it and the sheer thought of what lies ahead, if I wish to change the substrate, is daunting to say the least! I would prefer sand, everyone's argument seems to back this option, but would it be worth the whole process of making the change? :Thinking:

[Coral Cultivations]

My personal preference for deep sand beds is fine grade Aquamedic Hydrocarbonate - and is not that much more expensive than most sands if you buy it by the bucket. It has a very high calcium content too (this material in different grades is designed for use in calcium reactors).

For example, my shop system was 600 gallons, containing huge numbers of sps, lps and soft corals, including a substantial number of frags (resulting in high mucus levels (ie. chemical warefare between the various soft coral species), plus holding tanks for inverts - everything from hermits and shrimps to starfish and snails, plus small numbers of fish.

The filtration system was very simple:

1) Efficient mechanical prefiltration in each tank
2) Mechanical prefilter on the sump
3) Deletec AP902 skimmer (a three pump monster!)
4) Large deep sand bed 18x20 inches - 4 inches depth of fine grade Hydrocarbonate, full of mangroves (which when we closed the shop the roots of which had penetrated throughout the entire sump).

We used no form of chemical filtration, or any other phosphate or nitrate removing products. The phospate levels stayed at zero throughout and the nitrates at up to 1ppm (professionally tested).

Personally, I think all the skimmer did was remove the mucus and chemical products given off by the various corals, and the deep sand bed and mangroves did the rest, combined with 30% weekly water changes - not a bad result for a shop system?

Steve

[marcoz]

well it seems the sandbed is winning.. I've had a problem with high phosphate levels and wondered if it had anything to do with the gravelbed :roll: I shall change(although a logistical nightmare!) if it benefits the tank and it's inhabitants, especially if it saves buying phosguard - eventually I want to have a self sufficient eco system that looks after itself!! One can dream :whistling:

[Coral Cultivations]

Some of gravel brands on the market are full of phosphates - this may be the cause of your problem.

Steve

[marcoz]

I've been trying to work out the root cause of the phosphate problem for some time! Is there anything I can get in to clean the gravel until I change over to sand?

[flying Jock]

Hi

Can i just add that you need to be very carefull if you are changing sand beds.

It is not a case of just pulling out the old sand or or gravel as this will harbour nitrifying and denitrifying bacteria.

I learned tha hard way and lost around £1500 of sps and lps.

Also i see no reason to use silica sand which is indeed a natural sand found on many reefs.

Do not listen to the old wives tale of it releasing silicates as it does not (your tank is made from silica sand)!

I have use it as part of my DSB's for nearly 7 years and i have had no problems.

I mix it with normal coral sand at a depth of around 2"-3".

Do not see any point of buying expensive argonite sand as the claim of it releasing calcium has very little scientific proof as to how much calcium it will release and as i add calcium through a calcium reactor and kalk stirrer i would rather spend my money on other things.

Just my wee bit! :roll: :wink:

FJ

[marcoz]

thanks FJ, so what tips do you have for changing over the substrate? Also can anyone suggest a good gravel cleaning critter? :o

[Macca]

FJ, Silica sand as you say does not leach silicates but does nothing to buffer your water like true coral sand. Also the silica sand that is sold in pet shops are being supplied by builders merchants from land sites not the sea!

James

[Coral Cultivations]

Sea Cucumbers are ideal animals for a deep sand bed, they do a great job.

Steve

[flying Jock]

Yes indeed James hence why i prefer a mixture of the two! :wink:

As i said i have run mine for nearly 7 years now and i have 3 DSB's all set up exactly the same way.

Around 45 fish fed 4-6 times per day and zero nitrates speaks volumes for silica/coral DSB's and of course the massive 40kg of LR that i have in my reef also helps in the denitrification.

I personally would not say that if i had used only coral sand or argonite sand in my tank that it would have such a big effect on the buffering capacity of it.

Yes it does help but i will keep to my wee cheap mixture! :wink:

If i were to change a tank from gravel to sand i would remove all living animals including LR.

You will encounter die off from bacteria and trust me it is not worth taking the risk.

I would disgard the gravel and then put in a mixture of the sands you wish to use.

Add LR back in and run skimmer with some carbon and make sure parameters are fine.

When happy with that then i would add fish, corals etc :grin:

James does some great deals on critters for DSB's and i have only ever bought from him! :wink:

Good luck

FJ

[marcoz]

thanks again, I'm always looking to improve things and this sounds like a good route to go :)

[Chris, Reef Ranch]

Please see also denitrification topic on this forum.

For complete denitrification using a DSB of 2-5mm grain size sand you only need 1 inch!! Surprising isn't it. The reason being is that you are trying to produce a microaerobic environment not anoxic! Anoxic environments cause putrification and hydrogen sulphide (H2S). H2S is as toxic as hydrogen cyanide to fish so for those of you with DSBs don't disturb them with burrowing snails or sand sifters.

If you increase the grain size you will need to go deeper and visor versa.

If you are intending to run a refugium you need an extra depth so that zero oxygen areas do exists. This causes nitrate and ammonium to rise back up through the bed to nitrify algae. No need for mud but if you do use mud (expensive) then Bob recons that you need less than 1 cm for complete denitrification (cheaper!).

[Chris, Reef Ranch]

Don't use DSBs plenums in aquariums they fill up with detritus and cannot be cleaned because of the H2S.

My previous post had a bit missing! I will try again. Bob Goemans has communicated personally on the above information. He wrote secrets of living sand! You can rely on Bob's information.

Chris

[marcoz]

Op

[marcoz]

Operation deep sand bed update:
after a stressful day in a bucket for the inhabitants of my tank they are finally back home and with a new floor - A 2.5 inch sand bed made up of 3 different grain sized aragonite sand (got it cheap!). I hope the benefits will soon become apparant to the aforementioned residents... it certainly looks good! :party:

[Dons1903]

it certainly looks good! :party:

Pictures? :wink:

[marcoz]

sorry, no can do until I get a digital- it's on my ever growing list of necessary purchases! :roll:

[liquidlogic]

Sand obvisouly, better for live stock as passive through gills better etc,
looks nicer
doesnt trap dertrius as easy,
if you where a snail you try turning over coral sand 8)