My brother called me tonight and asked me if I would come down and help him clean his tank. He has a 55 gal with 4 colombians and 2 iridescent sharks in it. They are all about 7-8 inches long. I told him I would and asked when the last time it was cleaned...he asked when the last time I helped him was. It was a year and a half ago. That was the last time it was cleaned. Horrifying in itself, but agreeing to help him is rather daunting because I don't know how to go about doing it.
Do we clean it as good as we can in one shot? Do we do it in small doses so the fish aren't shocked from going from filth to clean? HELP!!!!
He hasn't tested the water, I'm scared to see those results.
The only thing he has done for around 18 months is add water and prime.
He has a UGF with only two air tubes so I know there is going to be a wealth of crud underneath.
Any advice will be appreciated. My advice to him was give me the tank if he's not going to take care of it.

Siphon it out, perhaps 30-40%. Move all the ornaments out of the way, make sure you siphon out all the spots of gravel. Test the PH of the tank water and match it up with the new water, as well as temperature. Scrape the glass pretty good with a new razor blade. If its acrylic, scrub it clean with the proper cleaning pad. Perhaps change the air stones in the uplift tubes as well, maybe even disconnect those and give them a good cleaning as well. Pull the gravel away from the stems so it does not fall inside when you take them off.
The good thing is your catching it before a problem occurred!

I don't know how those fish have survived!!! I thought my nitrate spike was bad, but I'd rather deal with that than this.
I will do as you suggested and I told him about the powerhead set up. He said we would go tomorrow after we clean the tank to get them and wait a few days to set them up.
He tested the water and got back to me. Everything is WAY high...I don't remember the numbers but NOT good. I do remember the PH was 9.3. We have the same tap (county) water and our PH runs the same Straight out of the tap is 7.2-7.3. How do we get it that high? I know about chemicals to lower the PH but to raise it that high?
He said one half of the glass is solid green (sunlight hits that side for several hours per day).
I'm just worried that we're going to end up killing the sharks. The last time I saw the tank up close, they were absolutely beautiful.
Keep your fingers crossed. I still want that tank. Maybe I'll make him do most of the scrubbing and he'll just say 'take it'.

Done. Never again. Took 5 hours. Murphy's Law attacked us...and his dog knocked me off the chair I was standing on... I hate that dog.
The good news is that the fish, so far, seem ok. Time will tell.
Thanks again for the advice.

lol @ the dog
Good work! Does he have some odd type of rock in the tank that could be dissolving and leaching something into the water to raise the PH?

That dog is lucky she could scramble to get up (I landed partially on her after I was body slammed on the dresser and bounced off it, yes, I said bounced) and run down the stairs quicker than I could. I really can't stand that dog!!!
The only rock he has in the tank is called Texas rock. Around here anyway, and it's been in there for years. I have the same in my tanks. Everything else is plastic.
He promised to test the water on a regular basis and do scheduled WC after a lot of nagging and arguing.
He'll set up the powerheads in a couple of days if the fish are ok.

That sounds like the limestone 'holey rock' found in Texas . A lot of people use it in african cichlid tanks to keep the Ph up AND because it's beautiful .
It is also somewhat lighter than other rocks and can be used to make great caves .

Yep thats the reason for the high PH, as Pete pointed out. I had a feeling there was some rock in there that was doing it, glad we figured that out.
I found this site that sells those rocks http://www.texasholeyrocks.com
We used to sell those where I worked and oftentimes I would stop people at the cashier and make sure the rocks would be alright for their tank, IE, if they had african cichlids.

And we must remember that the higher the PH, the more toxic the ammonia becomes.
So any buildup of waste, or overstocking, overfeeding, etc. may wreak havoc on a tank with such a high PH.

Ok. I understand what you're saying about the rock, but I have it in my 29 gal and the PH is always in the 7.2-7.4 range. The same as my 44 gal-doesn't have holey rock. I don't put anything in it to lower the PH. I use Prime and do reg WC. Is that why mine doesn't go up? It's from the same piece of rock his is, we cut it in half.
One of my brother's Colombians was dead this morning when he got home. Said the others seemed to be ok. I hope.
Explained the water parameters to him and told him what to watch out for, he didn't know a thing. His wife was always the one to take care of the tanks.

Thanks for all the help you guys have given me!
Donna

Regular water changes will definately keep things regulated . The rock will release minerals into the water and they will acumilate thus raising the hardness and Ph .
The same can be said for the opposite side of the Ph scale. In a normal tank ,without the limestone, (or with very little) the Ph will drop over time as a result of biological activity .
This is where many fishkeepers fail ! Too many people will go too long between water changes .As the water evaporates they replace it and the Ph is either climbing or falling the whole time .Then , after the tank begins to look bad , they do a large water change . This rapidly alters the water parameters and results in fish loss and/or bio filtration failure .

Also , the amount of mineral dissolved from the rock may be relative to the volume of water flowing across or through it .

Hi Donna, sorry to hear about the loss. The big shift in water parameters probably did it.
The tank needed to be cleaned though, you did the best you could have done, it would have been worse had it been put off longer, though.
Perhaps your WCs are keeping it from raising so high in your tank, nothing to do with the prime, really. It's interesting to hear that it's the other half of the piece thats in his tank, so they must be dissolving as fast. Surely though your PH would rise higher if given enough time between water changes. You are doing the right the as far as husbandry goes by changing the water as often as you do, good job.

Well, they all died. Shame, they were truly beautiful. He's starting over tomorrow. We dumped the whole aquarium this evening and gave it a thorough scrubbing. Says he'll do it right this time, now that he knows what to do.