low ph in ro water

J

jbgood

AC Members
Oct 1, 2005
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i have a 125 gal. that evaporates about 2 gallons a day. my ph is always low . is it becuase my top off water is reading 6.0 ph and 0dkh and what can i do to fix this? thanks john
 
Not sure, but low PH is a serious problem and it requires a solution.
Let's start by getting a clear picture of your setup.
Start with how long ago you started the system; what is your tank's history, filtration, biomass, etc. all the details please.
Regarding water loss, do you have cover on it, also just to be sure, have you checked for a leak, sometimes they can be slow leaks in the back, or a loose hose fitting behind the tank or sump.
 
ok, i have a 125 gal.with wetdry system,berlin skimmer,running a steralizer, with four 72inch 110watt vho 2blue, 2white actinics in a canopy and a little 3" fan to cool.always had a evaporation problem. there are no leaks. my ph stays low around 8.0 or lower,my alk is 9dkh,calcium 480,nitrite0,nitrate0. its always gets a lot of brown and green algae,no coralline. its been set up for about 7months.if im missing anything please let me know and thanks for the responce.
 
RO water will always have a low pH. It has no buffering (hence the 0 hardness), and will pick up CO2 from the air, which will make it somewhat acidic. The buffers in your salt mix should deal with that. What solt mix do you use.

pH 8.0 is nothing to be horribly concerned about. It would be nice to have it higher, but it's tolerable. Potential causes include low alkalinity (not a problem for you) or high CO2. It's surprising how many people have high CO2 (from low ventilation) in their tank rooms.

I lose about 1.5 gallons a day from my 90. 2 gpd in a 125 sounds pretty normal to me.
 
what about my top off water ,i dont use salt. i use instant ocean for my water changes. thanks
 
jbgood said:
what about my top off water ,i dont use salt. i use instant ocean for my water changes. thanks
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I guess I wasn't clear. You should expect your topoff water to have a low pH. When it enters the tank, the buffers in the saltwater will bring the pH up. Because the RO water is totally unbuffered, the acidic pH will have almost no effect on your tank water.

Here's a little test for whether your low-ish pH in the tank is due to CO2. Take some of your tank water and aerate it heavily (outside, or in a well-ventilated room) for 30-60 minutes. Then check the pH. If it goes up, you have a CO2 problem, either from too little circulation in the tank or too much CO2 in the room.
 
You might drop an airstone in the tank or down in the sump of your wet dry, that will drive off CO2 and help your PH.
 
When you do water changes how large are they and how often are they done? And what is the readings on your change water (not top off water)?
 
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