It won't help at all and may even hurt if the cause is elevated CO2 in your home air (as it most often is).
This has more:
pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/
from it:
The Aeration Test
Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.
Solutions to Low pH Problems
Some solutions to low pH problems are peculiar to each cause, and these are detailed is subsequent sections. Some general solutions, however, are frequently effective. Water changes are generally not an effective long-term solution to any pH problems. Effective solutions for low pH problems include regularly using high pH additives and providing more aeration with fresh (low CO2) air.
The more common cause pf low aquarium pH is elevated indoor carbon dioxide levels. As an aside, it has nothing to do with oxygen.
People can reduce the carbon dioxide in the air that a reef tank is exposed to in several ways. These include:
- Opening windows near the aquarium or sump. This option is cheap and effective if the weather is suitable.
- Bringing an airline from outside to a skimmer air inlet. Make sure the line has an adequate diameter to not excessively restrict the flow (or use a pump).
- Using a whole house air exchanger. Expensive, but effective.
- Plumbing a CO2 scrubber into an airline bringing air to a skimmer. These scrubbers are filled with a CO2absorbing material that needs to be replenished periodically. This method works well but can be expensive.
- Growing macroalgae, or any other rapidly photosynthesizing organism, in a refugium. This effect can also be timed to happen at night when the aquarium most needs a pH (and, fortunately, O2) boost.
Note that any chemical additive that raises pH in an aquarium will necessarily add alkalinity as well. There is no way around this issue. These products are detailed below.
- Limewater (kalkwasser) is the best choice as an additive for raising pH. Since it is a hydroxide additive, it has the largest possible pH rise per unit of alkalinity. It also ads a balanced amount of calcium so alkalinity does not rise relative to calcium.
- Sodium and potassium hydroxides (such as Aquavitro Balance) have a similar boost to pH per unit of alkalinity as limewater, but do not provide calcium.
- High pH two-part calcium and alkalinity additives generally contain carbonate and possibly some bicarbonate. These products have the advantage of raising pH without undesirably raising alkalinity relative to calcium, but the pH boost per unit of alkalinity added is about half that of limewater.
Do not worry too much about calcium or alkalinity rising from the addition of limewater to solve low pH problems. The demand for calcium and alkalinity rises in a reef aquarium as pH rises, so the net effect may be little change in calcium and alkalinity. Most often, the pH rises and no other problems are encountered. In any case, try these methods first and worry about such rises only if they happen and if they seem excessive.
Buffers alone are not generally a good method for raising (or lowering) pH because they raise (or lower) pH relatively little, and often result in excessive alkalinity. Unfortunately, the labels on many commercial buffers are written in ways that convince aquarists that their pH will be fine if they just add some buffer. More often than not, the pH is not improved for more than a day, and the alkalinity rises above desired limits.
A final method that is generally useful to increase pH involves growing macroalgae that absorb CO2 from the water as it grows. The growth is often in a sump that’s lit on a reverse light cycle to the main tank to provide the maximum pH increase when the main tank is at its minimum pH. The effectiveness of this effect depends on the amount of macroalgae and how fast it is growing.
