not that i mind, but i get the feeling im being trolled maybe not but i'll bite for mutual lulz just in case before I head out.
how are you working out mana recovered per second? base rate is 60 seconds to fill from empty.
800/60 = 13.33 mana recovered per second base
375% = 4.75 x multiplier since a 1.0 multiplier is the base rate every 10% is an extra 0.1 added to the base 1.0 rate
13.33 x 4.75 = 63.3 mana per second. not 30
a free super mana potion every 8 seconds

we dont just stand still holding down right click though, or at least not on a mod that is advertised as challenging. every fight that matters has periods of downtime for dodging and recovering hp or chasing/positioning unless you are just straight ES tanking like a champ.

Mana Management:

• Travel with a team to save mana. This way ally's effects (Damage, enemy debuff (e.g. SlowMissiles), ally buffs (e.g. Meditation), etc) will help. Mercs count too.
• Get more mana (Lum runes, Stats in Energy, gear like "Hatred" or PeltaLunata, etc).
• Use spells efficiently: maneuver so that enemies are bunched up for radius-effect spells (e.g. FireBall) or are lined up for linear-AoE spells (e.g. Lightning). Often a Merc or summon can help wrangle monsters (e.g. monsters bunch together around a focus), but sometimes they're exactly what you don't want (e.g. monsters chasing only you might line up well for linear AoE).
• Try to find sources (some example Uniques, Sets, and "Runewords" given, but some of these benefit the whole party so anyone could have them) of the following mana-skills: SolarCreeper (Wormskull), Redemption (SoulHarvest), Meditation (Heaven'sBrethren), Warmth (Trang-Oul'sAvatar) & SpellMasteries (Fire, Cold, Ltng, Magic, and Pois all come with a little ManaRegen in additon to letting your spells be more effective; e.g. "Jealousy", Templar'sMight, or BlessedAmulet), FindPotion (now finds Megas in NM and Ultras in Hell; e.g. Atma'sScarab), BattleOrders ("CallToArms").
• Try to find sources of gear-based mana effects: +%RegenMana, Dmg-to-Mana (only HP lost to PhysDamage count for this, but it's very effective for front-line builds), MP/Kill, MPonStrike or ManaSteal (these two are best for attack skills). +%SpellDmg can effectively reduce the MP cost if you manage to kill mobs with one less casting.
• Do not level spells before you need to. If you're already struggling for mana, and leveling that skill won't cause it's damage to kill with fewer casts, then you're not improving things.

Diablo2 Mana Regen formula:

• Vanilla: MaxMP/120 * (100 + %RegenMP)/100
  - EG with 600 MaxMP and 300% RegenMP, D2 characters would regenerate 20MP/sec.
• HUv1.7: MaxMP/60 * (100 + %RegenMP)/100
  - EG with 600 MaxMP and 300% RegenMP, HUv1.7 characters would regnerate 40MP/sec.

Using the d2 formula, which is 120s for an orb, I assumed it was hardcoded.