How should I change my substrate (or should I bother?)

[us2sinrz]

I have a 120 gal tank that has been established for 8 months. It contains about 20 fish (mostly cichlids, a few cats, an oscar and a pleco). Very healthy fish that grow well. I've only lost about 4 or 5 fish over the 8 months, mostly from aggresive fish. I started out with plants but the little buggers dug all but 2 up (all will be replaced with fake ones). I have an undergravel filter and lots of gravel substrate. I am switching out the ug filter due to seemingly unchangable nitrate levels and the digging cichlids keep exposing it. I actually posted another post regarding changing out the ug filter (thanks for the responses).

Now I am thinking about switching the gravel out for sand but I think this may be too much of a switch. I'm looking for your thoughts on this topic. Should I just leave the gravel? Should I switch for sand to help keep up the PH level? If I do switch out the sand, what is the best method?

Looking for your responses. This is a great forum, filled with very helpful folks.

 

[goalorientation]

Changing the substrate;
There is no way to do this while the fish are in the tank without causing severe shock. Drain the water from the tank into temporary holding containers (preferably 5 gallon buckets) where you will then put the fish. You can even leave 10-20% of the water in the bottom of the aquarium, considering it doesn't bother your rock removal. After the fish are out of the aquarium the race is on, because I wouldn't keep them in this condition a minute longer than necessary. Considering you did everything "right", you should have about 120-180 pounds of gravel to remove (once again keep a container in mind). Thoroughly cleaning the inside hard-to-reach corner areas may be a good idea at this point because you never know when you can reach these areas again. If you plan on reusing the rocks in the future I would wash it off fast so the algae doesn't dry and stain the rocks. If not you can always decorate your house the rocks. Add 50% cold water from tap to the tank, or just enough to get the heater running. Add new substrate. (At that size of a tank, or any size tank for that matter, consider completely discarding the UG filter because they're more of a nuisance than an asset). Use a water conditioner to treat the chlorine and alkaline's. Now would probably be a good time to add stress coat directly to your fish buckets, because they're nearly ready to be transferred back. When the temperatures are even, flip the buckets back into your tank and your task is complete.

The above I give as a rough hypothetical situation that is also realistic in your case. You may need to alter the process specifically to your immediate needs. Keep in mind the overall process will be grueling, stressful, and time consuming. I recommend putting on paper your exact steps in a visual plan for you to follow in case you get off track. Estimated time is between 3-6 hours.

 

[BrianNY]

I wouldn't bother changing the substrate. If you've got a nitrate problem it's probably because your tank is overstocked. Lots of cichlids will produce lots of waste.

You also need to know that a UGF utilizes the substrate for your bio colony. So shutting it off will throw your tank into a new cycle. If you don't want to remove some fish then you need to step up your maintenance. Cut back on feedings and do daily 25% pwcs until the nitrates get into the safe zone.

 

[us2sinrz]

Thanks for the responses. I figured the process would be a great undertaking which is why I thought I'd run a post first. I'll check for a few more responses and then report back my decision.

 

[BillD]

Brians response is right on and to the point. A UGF will not resilt in more nitrate than any other type of filter. The nitrate level is a direct product of the bioload, and the water change regimen. The digging, and exposing the plates is a problem though, as it will reduce the filters efficiency. It appears you need to step up your water change regimen to keep the levels lower.

 

[grottosandfins]

Personally, I would leave the gravel.

 

[DeFeKt]

First things first, I'd recommend running another filter alongside you undergravel for a few weeks, get the bacteria build up in that.
Step by step:
1. remove all the decor,
2. rip up the ugf, let all the mulm and crud settle for 10 mins or so,
3. gravel vac most of the crud out without taking to much water,
4. scoop out the substrate, leave the last bits of crud down the bottom.
5. pour your washed sand in.
6. let is settle for a while,
7. gravel vac lightly on the top and put your decor back in.

Its not that big a deal, and you can do it easily without removing your fish.
They will be just as stressed if you were to move them into a bucket then if they would be left in the tank.
I love sand substrates, good idea..

Matt

ps. turn off all your equipment while your doing it, ie. heaters burning out and pumps running sand through impellors etc.

 

[Guest]

I changed out my substrate with fish in tank. They will not get stressed especially if you do a little at a time. I have done this twice with no problems

 

[us2sinrz]

Thanks so much

All of the replies were very helpful in making a decision. I will keep the gravel as my substrate. I just bought a 50 gal - I'll put sand in that one. Thank you again for all of the knowledge.