Hi Klein,

Yes, it is important to adjust your pH on a daily basis.
Please see my web site from Australia for the reason. The problem is the availability of Iron, which drops off when you wander out of the pH range of about 6.4 plus, or minus about 0.3 Anyhow, my web site below explains it, please have a look and email me if you get stuck. The email address is on the web site.

Cheers,
Jimr007
Sunshine Coast
Queensland
Australia.

Here is a link that might be useful: Simple Sand Hydroponics

The type of pH adjustment solution and your water quality are important factors in controlling the pH. You can do a search with the key terms "pH" & will find many posts on this forum regarding this. There are many seasoned hydro growers from all backgrounds including scientists on this forum who have posted significant contributions regarding this topic.

Klein, In most cases, if you can keep your PH between 5 and 7, you will not have any problem. Watch your plants for an iron shortage which is usually the first symptom to show up. The new leaves will yellow between the veins.

For a PH that is slightly above 7, you can usually use ammonium nitrate for about 15% of your nitrogen source and lower the PH enough, or by adding chleated minors which can be picked up at a higher PH.

If your plants look good and are growing well, you are probably OK.

If the PH is too high and causing a problem, you can use small amounts of hydrochloric or sulfuric acid, always remembering that these can be dangerous to handle.

Norm

PH gradually increases over the week as your nitrates are used up. 15% ammonium nitrate (miracle gro) added to your solution (as was mentioned) is a great way to keep your PH in check. It's a lot easier than adjusting your solution with acid avery day.