So.. found out my tap water PH is somewhere around 8.5

you can buy a ph reducer at any lfs. they up and downs like 6-6.5 7-7.5 and etc etc.

You need a GH and KH testing kit. This will let you know the hardness of your water (GH) and buffering capacity (KH). PH does not determine hardness of water, only if the water is acidic or basic. It is possible to have soft water (GH) and still have a ph of 8.0 and above. Without changing the KH, chances are that the PH will bounce back to the original value. With a high KH, for instance 8 degrees, the PH reducer will only be temporary. I've tried PH reducers and it only worked for a less than a day. The best natural PH reducer is peat pellets (e.g. Laguna Pond Peat Pellets) since it will lower GH, KH, and PH. Also, a nice side effect is that it will lower total dissolved solids (TDS) of the water that filters through it. This will need to go in a filter (AC 110 or Hot Magnum). Testing will need to be done on KH, GH, and PH. You will want to add enough peat to keep the KH around 3-4 degrees, any lower and you leave your aquarium susceptible to a PH crash from decaying waste. You can also get a reverse osmosis unit and use half of that for the new water to go into your tank, and you still have to determine the KH and GH of your new water (tap plus RO water) plus you should get a TDS monitor to water the levels. You don't want the tank to go from a 300pm TDS to suddenly a 100ppm TDS rapidly as that will mess with the osmotic regulation of the fish and kill them in a few days.

I'm just south of you, and don't experience the same thing with my SA and CA cichlids, and I have hard water, with the GH at 22 degrees (393 ppm). My PH hovers around 7.8-8.0. I change out my water every 3-4 days as well, roughly 50 gallons per water change of a 240g tank.

Maybe it is something else that is causing your fish to get sick. There are quite a bit of folks in orange county, who I am sure are on the same water supply as you.

What fish do you have or had, include the ones that died?

How many?

What did you do to acclimatize the fish?

Where these store bought fish or ordered online?

When you say your tap water is 8.5....is that a measurement of the tap water right out of the tank? Or is that a measurement of the tank water's pH after it's been in the tank for 2-3 days. I had a similar problem when I set up my tank. I found out, pH of tap water is meaningless. If I take tap water, measure it right outta the tap, I get high pH values, too--8.4-8.6. If I let that tap water just sit in a glass for a day or two, pH measure 8.0-8.2. If I do a 75% WC on my tank with that tap water, and measure pH of the tank water a couple days later, I measure 7.6-7.8. When I added driftwood to my tank, that dropped my pH by 0.2-0.4.

I would highly recommend that you run a freshwater tank with the tap water you have. Playing around with kH, monitoring TDS, pH up and down, that's a lot of time and effort. If you slip, or make a mistake with all that, you get a tank of dead fish. Not saying it can't be done, but I personally wouldn't do it. If you really want to do it, though, read up about marine tanks and how they manage all these variables. They use RO water exclusively, and they monitor all this stuff. However, I believe it's easier for them since the sea salt they add to the RO water has all kinds of buffers in it to stabilize pH. Since you wouldn't be adding salt, you'd need to find some things to add to RO water to make it appropriate for a FW tank.

ragin_cajun said:

I would highly recommend that you run a freshwater tank with the tap water you have. Playing around with kH, monitoring TDS, pH up and down, that's a lot of time and effort.

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^^^This^^^

There's a lot of experienced fish keepers from SoCal on MFK and they seem to be doing fine with municipal water. IMHO I don't believe its the city water but most likely some other issue(s) that's killing your fish.

Yep I'm probably using same water source and my fish don't get sick nor showing anything unhealthy, I do have lot of driftwoods and plants in my tanks. Also, most LFS has trace elements to add for fresh water if you go with RO system.

All these fish new in the last week or so?

Are they eating regular pellets? If so, I would just saturate the pellets.

theedge634 said:

I'm in a 120 gallon tank with CA and SA cichlids. I've properly cycled the tank but have been having major issues preventing the fish that I add from getting sick. I do water changes ever 3 days or so, and constantly monitor ammonia, nitrates, and nitrites. The only issue that I have is fairly constant influx of diatoms, which I assume is from doing water changes with tap water. I'm starting to think that the common denominator for the fish that I add getting sick is stress from the extreme hardness of the water. How do I adjust and keep the water stable at a lower ph with this size tank?

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Are these the same fish you just got 2 weeks ago (according to your other thread)? How did you determine that they were all healthy when you got them?

By diatoms, do you mean algae? Afaik, diatoms grow in a wide range of pH and as low as 5.5 or lower. And high pH doesn't cause plants to exist. They exist where ever conditions are ripe for growth such as nutrients, oxygen, light, darkness, etc. pH might well determine which particular algae grows or how well it grows but it doesn't create algae.