The bigger the reservoir the more stable your pH and TDS will be. Similar to large bodies of water and how they hold heat/cold because of their sheer mass.

Seems like a large tree for just 2.5 gallons. What type of system are you using? ebb and flo (fill/drain) the bucket at intervals? If so I'd think you'd need at least a rez the size of your 10 gallon pot.

For scale I have a 55 gallon reservoir for (8) 5 gallon buckets. I grow tomatoes and I'm about to try strawberries.

--chris

I have a 25 gal reservoir for a 12-plant aero/hydro system.

Large reservoirs do cut down on Ph, TDS swings.

It's a drip system and I've buffered the solution, so the pH isn't completely unmanageable. How much of a problem will the TDS be? Is the tree using up all of its nutrients before its bi-weekly change?

I have no experience with trees, so take what I say with a grain of salt here. I would think your nute ratio would be just fine as long as you keep the resevoir topped off with water. I'm guessing the tree will drink the water up faster than taking up the nutrients and you want to keep the nutrients diluted. A larger reservoir will help with keeping the nutrients diluted as the tree will only take up certain amount of water in a given period. If the tree drinks a gallon per day you lose 40% of your water in your current reservoir which will impact the nute to water ratio much worse than losing a 1 gallon in a 10 gallon reservoir (10%). High nute to water ratio not only affects your pH, but it can cause the salts to build up worse in the medium and essentially wastes your nutes. It also could mean you have to flush the medium more often to remove excess salts.

I say nute to water ratio because I don't believe TDS is accurate based on what I read of your nutrient solution in another thread. Calcium sulfate in plaster of paris will not necessarily register on an EC meter until it dissolves enough and is floating, for example. That takes time as it generally takes microbial action to break it down, from what I understand. That doesn't mean it isn't there and pumping through the system, though. I may be wrong on this, of course.