We have acid in tpt but not it's opposite; alkali.  To implement Ph levels in tpt I came up with the following element suggestion and an alteration to CAUS:

Alkali (or ALKI):

ALKI is a powder.  It and ACID destroy each other upon contact.  Like ACID, it can't be made by reactions; only by brush, console and etc.

Opposite properties to ACID:

Whereas neutrons turn ACID into ISOZ, they turn ALKI into PLUT; this is a more efficient method of PLUT production than POLO+neutrons because ALKI is transparent to neutrons whereas POLO is opaque to them; it also doesn't produce photons like PTNM does when it converts ISOZ into PLUT.  ALKI absorbs HYGN upon contact and becomes LITH; this is opposite to ACID which is absorbed by LITH and the LITH, in turn, becomes HYGN upon doing so.  Whereas ACID has an extra dissoving effect on TTAN, ALKI heats TTAN up until the ALKI's life is too low (see below).

Heat and explosion catalyst:

ALKI sets off all explosives (except C-5 and LITH) upon contact.  It also ignites all flammable materials (except ACID, ANAR, and virus in any of it's states) upon contact.  ALKI starts with a life of 75 and as it ignites flammable elements, it's life goes down by 1; it dissapears when it's life reaches 50 or below or when it sets off explosives.  It does not heat up flammable elements as it ignites them and the resuting FIRE inherits the temperature of the flammable element it was created by or used to be; this makes it possible to burn WAX without melting it.  This rule does not apply to it setting of explosives and, as such, the resuting FIRE, LAVA, or PLSM will be the same temperature it would normally be.

Ice drill:

ALKI absorbs water varients (even FRZW) or PSTE upon contact like GEL or SPNG, leaving behind SALT, CO2, CLST, or ICE in the case of absorbing SLTW, BUBW, PSTE, or FRZW respectively; the two differences being that there is no limit to how much liquid it can absorb and it heats up upon doing so.  It also heats up on contact with ICE or SNOW.  As it absorbs water variants, or remains in contact with ICE or SNOW, it will continute to heat up until it reaches 3400C, hot enough to melt any metal except TUNG; it doesn't, however, melt into LAVA.  It can't evaporate water variants, even while hot; it would absorb them before they would get a chance to conduct heat from it.  These properties, along with one of the properties listed in "Misc properties" (see below) make simulating a drill (albeit one that drills only through ICE and SNOW) possible without CONV or void variants.  If ALKI is not absorbing water variants, or touching ICE or SNOW for 10 frames, it cools down until it reaches it's spawn temperature or until it touches or absorbs any the aforementioned elements.  It heats up by 20C for every frame it remains in contact with ICE or SNOW, or every 5 particles of water variants it absorbs. It cools down by 10C for every 5 frames it's not doing any of that stuff--after the 10 frame countdown, of course.

New CAUS:

CAUS is now the gaseous form of ALKI and not that of ACID; to prevent saves breaking, the current version of CAUS is renamed to CORS which is short for corrosive gas.  ALKI has 0.4% chance of absorbing WTRV and becomes CAUS as a result; the resulting CAUS doesn't inherit the ALKI's temperature.  The "absorb water without heating it" property of ALKI is, in fact, meant to prevent unwanted CAUS form forming.  CAUS has all of the same properties of ALKI listed in "Heat and explosion catalyst" (see above), but none of the properties listed in "Ice drill" (see above).  Upon contact with ACID or CORS, both it and the ACID or CORS will disappear.  The changes to CAUS and the renaming of the current version of CAUS to CORS are for accuracy sake; in real life, acid is corrosive while alkali is caustic.

Misc properties:

ALKI sticks to HEAC (even on it's underside) like GEL.  This property combined with the properties listed in "Ice drill" (see above) is what makes drills without CONV or void variants possible.  When ALKI is >=1000C, it starts to glow red and glows brighter as it continues to heat up.  When it's >=2900C it starts to shift from a glowing red to a glowing orange and gets more orange and glows brighter as it continues to heat up.  Although ALKI is usually not flammable, it turns into PLSM upon contact with molten TTAN or molten TUNG.