Changing a sandbed

[Jade5051]

I have a 75g established tank. It has a moderate bioload of about 1 seastar 5 fish, 5 corals, and 15 snails 15 hermits. The aquascaping is about 4-6 weeks old. The sandbed has been in there for years. Water parameters are decent pretty good but not TOTM worthy. Nitrates and phosphates are undetectable with a liquid test kit.

I don't like the sand I have in the tank, it's ultra fine and I would like to have something more coarse. Then I could upgrade my powerheads flow without creating a sandstorm in my tank. I want to remove the sandbed and replace it with something more coarse. I will quarantine all the livestock. Then remove the sand bed and replace it. Let it clear up for 1-2 days then reintroduce all the livestock.

What are your thoughts on removing the sandbed and replacing it with a clean new sandbed? Will the tank most likely cycle even with established rock and cycled water? Is this too dangerous? Do I need to wait and see if the tank cycles before reintroducing livestock? Any constructive comments and concerns would be greatly appreciated.

[killinit123]

if I were in this situation this is what i would do:

get pvc piping turn off all pumps and funnel the new sand through the pvc right over the existing sandbed... i would only do a little bit at a time though.. this way you will not have to remove the existing sandbed or Qt inhabitants and the courser sand will stay on top. its just a thought seemed like a good plan in my head

[PhaneSoul]

I would start vacuuming maybe 1/2 or a third out every few days then use the pvc method as described. I put sand into my 55g using pvc and had just a little clouding which was gone in a few hours.

you probably wont have a mini cycle, but depending on how clean your tank was in the first place your going to have a mini phosphate cycle. or in other words an algae bloom from the excess phosphate in the new sand

[Browndawg80]

If the sandbed is old as you stated you could be in danger of releasing hydrogen sulfide and nuking your entire tank if it's not removed safely. The easiest way to achieve this is to have as many brute trash cans on hand as it will take to hold all your water. Use a large piece of flexible hose ( 3/4 or 1" work best) and start siphoning water into the brute cans WITHOUT disturbing ANY of the sand. Once you get as much water out as you can ditch the hose and use a shop vac to suck all the sand out in one shot. Once this is done you can rig a piece of hose to any old mag drive or maxi jet pump and pump all your original water which is clean because you never touched the sand back into the tank.

I run my system bare bottom and love it so I can offer no advice on putting fresh sand back in.

This may seem like a lot of work but if you get everything prepped and have it on hand when you start the entire job shouldn't take more than 1-2 hours. Think of it like removing a bandaid, quick and done or a little bit at a time. If you don't have the brute cans just buy them and save the receipt, you can always return them since nothing touches them except clean SW. have a couple 5 gallon buckets on hand for your livestock and you should be good to go.

FWIW I would not put new sand over the old sand as these beds can and do go bad as they age. Removing a tiny portion every week could be problematic as you will no doubt be stirring up all kinds of nastiness besides the toxic H sulfide which may or may not be present. Better safe than sorry. Good luck.

[PhaneSoul]

didn't think of that, how deep is your sandbed? 1-3in and I don't think id worry about h-sulfide but any deeper then that and its probable

[Bpb]

I did this but the reverse. Went from crushed coral to a finer grain. It's easy if you're patient. I did it about 10% every week. Roughly. Took a couple months. Sandbed harbors so much beneficial stuff if you just pull it all out you're removing a massive amount of beneficial bacteria, pods, worms, and snails.

I would siphon out about 10%, pour the water back in, and sift out the snails. Then I'd add the new sand with a 3/4" pvc pipe and a funnel. Added the sand one scoop at a time with a measuring cup. Took forever. But was able to do this with zero cycling impact and even kept power heads on and had no clouding or sandstorm. It's nearly impossible to avoid mixing to some degree doing it this way, but it'll be alright.

When I say I removed 10% chunks I mean 10% in a little square section straight down to the glass and even tried to use some rubble to keep the sand from falling back into place. You could even use some diy acrylic boxes to keep the sand from mixing. Just ideas

[Jade5051]

Originally Posted by Browndawg80

If the sandbed is old as you stated you could be in danger of releasing hydrogen sulfide and nuking your entire tank if it's not removed safely. The easiest way to achieve this is to have as many brute trash cans on hand as it will take to hold all your water. Use a large piece of flexible hose ( 3/4 or 1" work best) and start siphoning water into the brute cans WITHOUT disturbing ANY of the sand. Once you get as much water out as you can ditch the hose and use a shop vac to suck all the sand out in one shot. Once this is done you can rig a piece of hose to any old mag drive or maxi jet pump and pump all your original water which is clean because you never touched the sand back into the tank.

I run my system bare bottom and love it so I can offer no advice on putting fresh sand back in.

This may seem like a lot of work but if you get everything prepped and have it on hand when you start the entire job shouldn't take more than 1-2 hours. Think of it like removing a bandaid, quick and done or a little bit at a time. If you don't have the brute cans just buy them and save the receipt, you can always return them since nothing touches them except clean SW. have a couple 5 gallon buckets on hand for your livestock and you should be good to go.

FWIW I would not put new sand over the old sand as these beds can and do go bad as they age. Removing a tiny portion every week could be problematic as you will no doubt be stirring up all kinds of nastiness besides the toxic H sulfide which may or may not be present. Better safe than sorry. Good luck.

The release of hydrogen sulfide was also a concern when I first thought of doing it. It's not a ton of work to drain the tank and suck out all the sand. It will probably take 1-2 hours like you said but I'm slow so it could take me 3 hours. I'll drop everything in a 5 gallon bucket while I'm changing it out. This will also give me the opportunity to move my aquascaping and stablize it on the glass bottom the way I want. While I'm there I should probably drill the tank and make it reef ready. The HOB overflow works great but why am I cutting corners when I'm going to lengths of changing the sandbed, diy custom sumps, diy handcrafted aquascaping. I'm going to have to recruit a friend for this cause moving the tank solo to drill it is quiet the task. Thanks for the advice I think I'll follow your method.

Originally Posted by PhaneSoul

didn't think of that, how deep is your sandbed? 1-3in and I don't think id worry about h-sulfide but any deeper then that and its probable

The sandbed is 1-3 inches depending on the area. I can see some pockets of hydrogen sulfide against the glass.

[Jade5051]

Originally Posted by Bpb

I did this but the reverse. Went from crushed coral to a finer grain. It's easy if you're patient. I did it about 10% every week. Roughly. Took a couple months. Sandbed harbors so much beneficial stuff if you just pull it all out you're removing a massive amount of beneficial bacteria, pods, worms, and snails.

I would siphon out about 10%, pour the water back in, and sift out the snails. Then I'd add the new sand with a 3/4" pvc pipe and a funnel. Added the sand one scoop at a time with a measuring cup. Took forever. But was able to do this with zero cycling impact and even kept power heads on and had no clouding or sandstorm. It's nearly impossible to avoid mixing to some degree doing it this way, but it'll be alright.

When I say I removed 10% chunks I mean 10% in a little square section straight down to the glass and even tried to use some rubble to keep the sand from falling back into place. You could even use some diy acrylic boxes to keep the sand from mixing. Just ideas

Thanks again. Too many good suggestions. Now I'm not quite sure what to do.

[PhaneSoul]

Originally Posted by Bpb

I did this but the reverse. Went from crushed coral to a finer grain. It's easy if you're patient. I did it about 10% every week. Roughly. Took a couple months. Sandbed harbors so much beneficial stuff if you just pull it all out you're removing a massive amount of beneficial bacteria, pods, worms, and snails.

your also removing all the organics fueling all this bacteria. removing a sandbed all at once that doesn't have h-sulfide is no big deal. in one shot your reducing the total bioload on the tank, nothing the rocks alone cannot handle.

face it, the only reason the snails and worms are beneficial is so the sandbed is somewhat maintained, and even that term I use loosely, the pods are more beneficial then anything because the fish feed on them. one can say the same about the worms, but not to the extent of pods.

if it were me with no sulfide, I would do it all in one sitting, but since you say you have HS obviously you need to work cautiously.

[Jade5051]

Originally Posted by PhaneSoul

your also removing all the organics fueling all this bacteria. removing a sandbed all at once that doesn't have h-sulfide is no big deal. in one shot your reducing the total bioload on the tank, nothing the rocks alone cannot handle.

face it, the only reason the snails and worms are beneficial is so the sandbed is somewhat maintained, and even that term I use loosely, the pods are more beneficial then anything because the fish feed on them. one can say the same about the worms, but not to the extent of pods.

if it were me with no sulfide, I would do it all in one sitting, but since you say you have HS obviously you need to work cautiously.

When you say work cautiously....are you worried about my health or the tanks health?

[Jade5051]

Originally Posted by Bpb

I did this but the reverse. Went from crushed coral to a finer grain. It's easy if you're patient. I did it about 10% every week. Roughly. Took a couple months. Sandbed harbors so much beneficial stuff if you just pull it all out you're removing a massive amount of beneficial bacteria, pods, worms, and snails.

I would siphon out about 10%, pour the water back in, and sift out the snails. Then I'd add the new sand with a 3/4" pvc pipe and a funnel. Added the sand one scoop at a time with a measuring cup. Took forever. But was able to do this with zero cycling impact and even kept power heads on and had no clouding or sandstorm. It's nearly impossible to avoid mixing to some degree doing it this way, but it'll be alright.

When I say I removed 10% chunks I mean 10% in a little square section straight down to the glass and even tried to use some rubble to keep the sand from falling back into place. You could even use some diy acrylic boxes to keep the sand from mixing. Just ideas

Curious, why did you go to finer grain sand?

[PhaneSoul]

Originally Posted by Jade5051

When you say work cautiously....are you worried about my health or the tanks health?

the tanks health. h-sulfide just smells like rotten eggs, plus I haven't heard of anyone dying from the smell

https://www.osha.gov/SLTC/hydrogensulfide/hazards.html