Chem gurus: how to raise pH in tap water - The Planted Tank Forum
 
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post #1 of 4 (permalink) Old 06-28-2005, 02:15 PM Thread Starter
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Chem gurus: how to raise pH in tap water

Hi all,

Two months ago, my untreated well water came from the tap at ph 5-something and outgassed to 7, so it is known to have very high dissolved CO2, making it acidic water. The normal state for my tank is to run it in the pH 6.6-6.8 range. After a water change (about 50%, weekly) the tank pH drops from 6.6 down in the high 5s for about 10 minutes, then it recovers to about 6.2 and gradually ramps back up to 6.6-6.8 over the rest of the day, and the plants pearl like mad and the CO2 eventually kicks on late that day or the next day and mostly stays on for long stretches. The pH controller is set to activate at 6.8, so my tank runs in the 6.6-6.8 range on a normal day.

In the last month, I noted that my CO2 was not kicking on much at all, so I TWICE recalibrated my pH controller (using sealed pinpoint 7 packets), tested my water, and noted that my water was rarely rising above 6.6, even after hours under the lights. I cleaned the filter and intake to make sure this is not the issue.

I then thought to test the tap water, and now it consistently runs pH 4 something. I am thinking a non-CO2 acidity is now in my tap water in addition to the CO2, making the water more acidic, and leaving it more acidic after outgassing.

So I am thinking I need to either hike the KH or hike the pH to get my CO2 to kick on more often. The plants are telling me something is not right, and I think it's the CO2 levels.

Fish are fine with this, but plants are showing signs of a deficiency (pearling is not aggressive like it was before this tap water pH change, growth has slowed, some are showing puny growth or signs of stress algae, very subtle, but I see they are not as happy). They are getting full EI ferts, so I am thinking first it's lowered CO2 levels before I look for a nutrient deficiency. I'm running the tank at KH8 GH5. Tap is basically KH and GH zero, so it's all supplemented chemically.

I would like to temper my pH a bit but don't know if I should just hike the KH more, or if I should get some base and actually hike the pH a notch. I have some Jungle Labs pH increaser, but when I called them they were cagey and wouldn't divulge if it's a phosphate buffer product or not. The last thing I want is a phosphate (or any other) buffer.

Does anyone have suggestions, or know if the Jungle Labs pH increaser is just a base?

Tank is 75 gallons, heavily planted, low bioload (about a dozen neon size fish and a slew of baby cherry shrimp and various snails). Light is adequate. I had great, healthy growth and heavy pearling most the time before this water quality change. I have no algae issues except a significant Cladophora presence that I am also battling.


Thanks!

Donna
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post #2 of 4 (permalink) Old 06-28-2005, 11:57 PM
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What is the kH of the tank? If it's low just add baking soda and both the kH and the pH will come up.

You might have a case here where you need to aerate the water before adding it to your tank.
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post #3 of 4 (permalink) Old 06-29-2005, 12:12 AM
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You state you keep your KH=8. As Rex indicated, you must be adding something to do this, right? If the KH really is 8, I don't understand how your pH could really be that low. Perhaps it is the method you're using to raise your KH?

As to outgassing, I refill my tank with a python. During the refill, I point the output of the hose more or less horizontal and have it running near the top of the tank blasting into the side of the tank. IMO, this agitation will help *some* with the outgassing, speeding up the process slightly.
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post #4 of 4 (permalink) Old 07-02-2005, 02:37 AM Thread Starter
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Thanks

Thanks for the replies. I think I may have two phenomena happening here, after the events of this week. The first is, I discovered my prefilter was totally clogged (even though I had just changed it about a week ago, but I have been doing a lot of disturbance to the tank and added some new turface, so the fine particles apparently clogged the prefilter jacket.). This resulted in much reduced water circulation throughout the tank. I only discovered it last night when I came down to hear the eheim making strange noises, like it was airlocked, which it was. I finally figured out the clogged prefilter put such a load on the eheim that it airlocked itself (like it pulled so hard it brought bubbles out of solution). So, I think the greatly reduced circulation was greatly reducing the availablility of CO2 in the water, and thus the very slow change in pH, even when the CO2 kicked on finally.

Second, I think I have a nutrient deficiency in the tank. Some things are just not looking right. My Crinum calimistratum is now showing yellowing and fading of the ends of the leaves. The Ludwigia ovalis, which should be growing like a weed, is stagnant. The Ranunculus papulentus, which was doing great a month or two ago, now shows smaller "umbrellas" which are curved down and under. I see some holes in other leaves throughout the tank. I suspect magnesium or calcium, as the snails are also looking ragged with poor shells. I supplement the tank to GH 5 with calcium chloride and epsom, but perhaps that is insufficient?

The tank water is boosted to KH 8 with sodium bicarbonate. Ferts include fleets, KNO3, K2SO4, Watson micros with iron.

Any opinions on these thoughts? I appreciate your insights.

D.
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