12-01-2008, 10:06 AM
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8.8? Wow. First off with a parameter that out of whack I'd recommend taking a sample to your LFS and seeing if they'll do a test on it just to confirm that number. Not questioning your ability to do a test but with a something that far off I'd get a second opinion just to be safe. If it is 8.8 then your water is more alkaline than even a saltwater set up.
Lot of things to consider here.
1) Altering your pH. From what you're saying you have a tank already set up and want to change the pH correct? If so you'll need to do things slowly. First off get a couple of gallons of reverse osmosis (RO) water for testing. Make sure its actually RO water and not something that's just filtered and being called something misleading. Check it with your pH test, it should read 7.0 on the dot. Now, how to alter things. First get a bucket, actually you'll probably want a couple, and a measuring cup. You need to determine what ratio of tap to RO water will provide you with the pH you're looking for. Keep things realistic, 7.0 isn't perfect pH, it's just a pH. 7.5 or 7.8 will be more than enough to keep pretty much any freshwater fish you'll ever want to. Use the measuring cup and make a mixture of 50/50 RO to tap water in a seperate bucket and test the pH. If the pH is still high you'll need to alter the mix up and if it's way low then use less RO. Always start with a new mix, don't alter the one you've got, and always test the water don't just assume. Keep in mind that the pH scale is logarithmic and things start slow but can start to move very fast so use small steps and keep them simple if at all possible. Ratios like 1:1 or 1:2 or 2:3 are easy to mix, something like 23:78 is going to be next to impossible. Get it close. If you're a point or two high or low that's better than having an odd ratio you'll never be able to maintain.
Once you have a good ratio and confirmed that the pH is where you want it you have to figure out how fast to add it. How much water do you usually change? I usually do a 30% water change myself. So in my case to gauge the effect that a 30% water change with the new mix I'd get 7 cups of water from the aquarium and add 3 cups of the mix to it. Now measure the pH of the new mix. If it's changed more than 0.3 points you need to reduce the amount you change, if its changed less... well don't worry about it. Why is this important? A rapid pH change can kill your fish as fast as an ammonia/nitrite spike. You have to change the pH slowly so your fish can adapt to it. By using the new water mix for water changes you can slowly bring the pH to where you want it over the course of several weeks/months and not stress your fish. Don't just hope the amount you change will be safe, test first. Also test out the water change ratio each time you go to change water. Remember, the pH can change fast. The ratio that only moved it 0.3 points last time might move it 0.5 this time. Better safe than dead fish.
Once you have your mix established and your water change ratio you are set. Just keep using that RO to tap ratio and keep your water change ratio the same and you're good to go. If you had to reduce the amount of water you change to keep the pH change small once your pH is within 0.3 points of where the mix is then you can go back to your regular water change ratio.
2) RO systems. Like iamnbatman said it may be cheaper in the long run to simply buy your own RO system. After you do the first step you'll know how much RO water you need a week for your water changes. Now multiply that by 52, that's how much you'll spend on RO water in a year. Now start comparison shopping for an RO system. RO systems are rated in gallons per day (GPD) so keep that in mind when you are looking. If you do a ten gallon water change that would take 10 hours to get the water you need with a 25 GPD system but only five with a 50 GPD system or 2.5 with a 100 GPD system. It all depends on how long you're willing to wait for your RO. Personally I wouldn't go with less than a 50 GPD system just because of how much time it would take to get the water your need. Take a look at the life expectancy of the RO system's consumables, membranes and filters. Figure how much you'd have to spend a year on replacement parts and with your high pH I'd plan on going with the low end of the life estimates. Don't forget to add in costs like the large container you'll need to hold your RO water as its made (I've seen virgin trash cans used by a lot of saltwater people who depend on their RO system), or the cost of the install if you don't feel comfortable doing it yourself. Add your initial costs for the RO system up and then just add the consumables cost per year to it for each year it operates. Compare that cost to what RO water costs over the same time frame.
For example (very rough numbers): I can buy RO water for a dollar a gallon. I need five gallons per water change. That means I'd need 260 gallons of RO water a year and spend $260 for it. I can buy an RO system for $150, a container for $80, I can do the install myself and I'll spend $50 in replacement parts a year for the system. My initial start up costs are $230 and it costs me $50 a year after the first year. As you can see in this example even if I replace the RO system completely every year the system pays for itself. If RO costs me $0.50 a gallon the system will pay for itself shortly after the second year.
Unless the RO water is being sold VERY cheaply the odds are good your own RO system will be cheaper in the long run.
Oh, and one other factor, RO systems make a lot of waste water. Most of them create 4 to 6 gallons of waste water for every gallon of RO water they make. In other words your 50GPD RO system will make between 200 and 300 gallons of waste water. If you only need 10 gallons still expect to have to dispose of between 40 and 60 gallons of waste water.
3) Do not move fish out of that quarantine tank and into the main tank. A pH change of that degree will very likely kill the fish. I'd use that tank of water for your initial testing of how to move your pH.