Can't Keep Plecos Alive For More Than A Day Or Two

[esoterix]

[SIZE=9pt]I am having a hard time keeping algae eating bottom feeders (plecos, Chinese algae eaters) alive in my newer aquarium. I setup a 65 gal back in March/April, it has pool filter sand about an inch thick for ground cover. I have some pieces of drift wood and java ferns for decoration. I have two canister filters, one of which came from another established aquarium. Tankmates are pretty easy going tetras (Congo, bleeding hearts) and a couple marigold variatus. [/SIZE]

[SIZE=9pt]I attempted to transfer a clown bushy nose pleco from my other aquarium and it died within 24 hours. I waited a month or two and bought a common pleco from the pet store and that again died within 24 hours. I tried a Chinese algae eater 3 weeks ago and it too died within 24 hours. No signs of disease or abuse. I saw a couple of them a few hours before I found them dead and they didn’t appear to be in distress (though it’s hard to tell with these types of fish). Prior to any pleco/algae eaters I added 5 albino corys. They all seemed happy for about a month and then I lost 3 of them over the span of 6-8 weeks. The two corys that remain appear to be doing well. [/SIZE]
[SIZE=9pt]My ammonia is at or near zero, same with nitrite, my nitrates have been ranging between 5-20, this may be the result of a variatus that died within a few days of introduction that I was not able to recover. Algae is an issue which is why I have been trying to place a pleco/algae eater in the aquarium. This could be from the higher nitrates and indirect light from a nearby window. [/SIZE]
 
[SIZE=9pt]I had suspected it could be related to a large piece of Malaysian driftwood I had bought for the aquarium. However I had soaked it for months and it has been in the aquarium since setup. Thinking it could have been contaminated – I removed the piece changed out some water and then attempted to add a new rubbernose pleco to the tank. It still died within 48 hours. I have hit a dead-end as to what is causing this issue…[/SIZE]
 
[SIZE=9pt]The PH of the aquarium is around 8.5 due to the local tap water. I try to do 20% water changes every week or two, and stir the sand to avoid toxic gas buildup. I have an aquarium with 2 plecos I want to take down, but don’t want to transfer the plecos if they are going to die.. The LPS and aquarium society have no idea why this is happening and I can’t find anything on the internet… Any ideas? Thanks![/SIZE]

 

[Byron]

This sort of issue is often very difficult to resolve, as one simply has to go through the possibles until one finds the cause.  The fact that upper fish appear immune would tend to suggest it is something related to the substrate, or wood.
 
Was there any sort of whitish fungus on the wood?
 
Are there plenty of hiding places out of the direct tank light for the pleco and corys?
 
The newly acquired pleco...did they have sunken bellies, or were they eating well?
 
Are any substances or chemicals [meaning, aquarium-related] entering the tank, aside from water conditioner?
 
The ammonia and nitrite...at or near zero suggests these are not "zero" permanently?  What do they rise to, and when in relation to water changes?
 
Pleco can be very sensitive, but I've always thought CAE rather indestructible.  BTW, the CAE is not good for algae, as it grows it eats less to none and can be very nasty to other fish.  And the common pleco is not good for algae either, and as it grows to more than a foot will be a problem in its own right.
 
I would increase your water changes; no less than once each week, and 1/3 to 1/2 the tank volume.

 

[esoterix]

The wood was clean when I put it in there and the only thing on it now is some algae, no fungus.
 
I have two pieces of driftwood, one fairly large, and java ferns for tank decor.
 
The pleco purchased most recently looked happy and healthy, no sunken belly.
 
Other than Amquel + during PWCs there are no other chemicals being used it the aquarium.
 
I’ve only seen the ammonia vary between 0-0.25ppm. The highest I've seen the nitrate has been 20, it tested at 10 last night before the PWC.
 
The only reason I went with a CAE was due to their hardiness and cost. If I can’t keep one of them alive I know the pleco isn't likely to do any better. My plan was to re-home the CAE once things were straightened out.
 
I have stepped up the water changes lately and will continue to do so. I just can’t figure this out… I agree that it is more likely be substrate/driftwood related… I think I got all fragments of the driftwood removed, but may have missed a couple tiny pieces before I added the last pleco, which I suppose could have caused a similar result if the pleco fed off it. I cleaned the pool filter sand before adding and my current corys don’t seem to mind it…