Skip to content
Plinth

· Private foundation

Helms Foundation Inc

Its FY2025 filing reports that it funds preselected organizations and did not take unsolicited requests; check the foundation's own site before ruling it out.

$176k
Granted FY2025still arriving
51
Grants FY2025still arriving
8
States reached
$10k
Largest
01What you fund
01100% classified

What you funded, over time

Every grant placed by its stated purpose and the recipient’s mission, by year — across FY20172025.

Education$525kAnimals$291kHealth$147kHuman Services$128kReligion$96kPhilanthropy$84kYouth Development$73kFood & Nutrition$53kOther$0
02FY2025 · 51 grants

Where the money goes

Your grants by size, and where they go.

By grant size · FY2025

  • Under $10k45 grants · $116k
  • $10k–50k6 grants · $60k
$2,000
Median grant
8
States reached
$3.9M
Total assets
Largest grants
RecipientAmount
THE GOOD SAMARITAN CENTER$10,000
SERVITE HIGH SCHOOL$10,000
ST JUDE MEMORIAL FOUNDATION$10,000
ROSARY HIGH SCHOOL$10,000
FRIENDS OF ALBERT WHITTED AIRPORT$10,000
KPAL$10,000
AOPA FOUNDATION$5,500
FRIENDS OF FREDERICKSBURG NATURE CE$5,000
THE GRACE CENTER OF FREDERICKSBURG$5,000
HILL COUNTRY COMMUNITY NEEDS COUNCI$5,000
FREDERICKSBURG ISD EDUCATION FOUNDA$5,000
BOYS GIRLS CLUB OF FREDERICKSBURG$5,000
ST MARY'S SCHOOL$5,000
FREDERICKSBURG SCHOLARSHIP FUND$5,000
GREY BEARS$4,000
02The need
03

Do your dollars go where the need is?

Each grant placed by the hardship in its grantee’s ZIP, then read against the area’s typical level.

show:

Your human-services grants (FY18–25, $54k) land where the poverty rate runs at 12%, against an area that typically sits at 9%. 100% of those dollars go to grantees based in above-average-need neighborhoods. Most of your grants land in higher-need ZIPs.

area typical 9%HELP A MOTHER OUT: $2k → 10%GREY BEARS: $4k → 13%SOUTHEASTERN GUIDE DOGS: $3k → 10%KIDS IN DISTRESS: $3k → 11%KIDS IN DISTRESS: $3k → 13%GREY BEARS: $4k → 13%SOUTHEASTERN GUIDE DOGS: $3k → 10%KIDS IN DISTRESS: $3k → 11%KIDS IN DISTRESS: $3k → 13%GREY BEARS: $2k → 13%SOUTHEASTERN GUIDE DOGS: $3k → 10%KIDS IN DISTRESS: $2k → 11%KIDS IN DISTRESS: $3k → 13%GREY BEARS: $2k → 13%SOUTHEASTERN GUIDE DOGS: $3k → 10%KIDS IN DISTRESS: $3k → 13%SOUTHEASTERN GUIDE DOGS: $3k → 10%KIDS IN DISTRESS: $3k → 13%THE GRACE CENTER OF FREDERICKSBURG: $5k → 10%0%20%40%50%more need →
grant to an above-average-need area below average· circle size = grant amount

Matched: human-services grants are those whose grantee’s IRS cause code is Human Services. Placed by people below the poverty linein the grantee’s ZIP, averaged from the tracts in that ZIP; grantee ZIP can differ from where services are delivered.

Which US states your grants reach

AK
ME
IL
MI
NY
OR
CA
CO
VA
MD
AZ
NC
DC
TX
FL

US grants placed by each grantee’s ZIP, which can differ from where services are actually delivered. Need from public data — U.S. Census/ACS, CDC PLACES, Eviction Lab, USDA — shown as context about the area, never attributed to your giving.

03Your edge
repeat funding

Who you back again

Which organizations you funded more than once, and which you funded a single time. Each grantee is matched to its own filings.

94%of every dollar goes to organizations you’ve funded before.
$1.5M · 78 repeat orgs$97k to everyone else

78 repeat relationships — 41 still active in FY2025, 37 since wound down; 8 grantees were first funded in FY2025 (too recent to call).

How the two cohorts compare

Re-uppedFunded once

Organizations

78
34

Total granted

$1.5M
$78k

Median revenue growth · since first grant

+25%
+32%

Still filing today

54%
59%

New vs renewed · share of each year

In FY2025, 89% of grant dollars renewed an existing relationship; $19k went to new ones.

50%100%’17’18’19’20’21’22’23’24’25
RenewedFirst-time

Where new relationships form · theme of each grantee’s first grant

’17’18’19’20’21’22’23’24’25
AnimalsEducationHuman ServicesHealthArts & CultureInternationalOther

First-time = a grantee’s first year in your filing window; renewed = funded in an earlier year too. As a portfolio matures the renewed share naturally climbs — once funded, an org stays “renewable” — so the signal is the years that buck it (a new-grantee intake wave). The earliest year is left-censored: relationships that predate the data read as “new.” Theme is the grantee’s IRS cause.

Backed again, and grew

  • TT
    The Thacher School Inc
    4× · 2017–2020 · $67k · revenue +32%
  • FI
    FREDERICKSBURG ISD EDUCATION FOUNDATION
    7× · 2019–2025 · $48k · revenue +306%
  • TA
    THE AOPA FOUNDATION INC
    9× · 2017–2025 · $45k · revenue +85%

Funded once

  • CK
    COMPETITIVE K9 OF ALASKA
    one grant, 2018 · $10k
  • NAVY SEAL FOUNDATION INC
    one grant, 2022 · $5k · revenue +10%
  • FD
    FREDERICKSBURG DOG PARK ASSOCIATION
    one grant, 2017 · $5k

Repeat = funded in two or more distinct years; growth and survival are read from each grantee’s own subsequent IRS filings.

04Your field

The map has a center of gravity: the average direction from the rest of the sector toward the organizations the foundation funds — the shape of its giving. Scoring every nonprofit along that direction surfaces the ones that look most like the portfolio. These are the closest matchesthat aren’t grantees — a resemblance in what they say they do, not a recommendation.

1
Marin Humane Society

Marin humane transforms lives through exceptional animal care, humane education, and advocacy. every day, marin humane inspires compassion and positive relationships between people and animals.

Animals
2
Society for the Prevention of Cruelty to Animals for Monterey County

The SPCA Monterey County's Mission is assuring compassionate treatment of all animals through rescue, rehabilitation, protection and education. The SPCA shelters homeless, neglected, and abused pets, including dogs, cats, horses, exotic…

Animals
3
The Humane Society for Seattleking County

Seattle humane promotes the human-animal bond by saving and serving pets in need, regardless of age, ability, circumstance or geography.

Animals
4
Pet Orphans of Southern California

In addition to rescue and adoption, pet orphans provides a wide range of services including education, medical/financial, spay/neuter, and training assistance.

Animals
5
Rancho Coastal Humane Society

See schedule orancho coastal is dedicated to the rescue and shelter of abandoned companion animals. it encourages adoptions into loving homes and provides educational and community outreach programs designed to enhance the human-animal…

Animals
6
Progressive Animal Welfare Society aka Paws

A champion for animals since 1967, PAWS is a nationally recognized leader - rehabilitating injured and orphaned wildlife, sheltering and adopting homeless cats and dogs, and educating people to make a better world for animals and people.

Animals
7
Santa Barbara Humane Society for the Prevention of Cruelty to Animals

Santa barbara humane operates two campuses located in santa barbara and santa maria providing care for community-owned and homeless animals. both campuses offer affordable high quality veterinary care, compassionate behavior training…

Animals
8
Silicon Valley Pet Project

Silicon valley pet project (svpp) is a 501(c)(3) nonprofit organization committed to saving local at-risk shelter pets through rescue, community involvement and education.

Animals
9
High Sierra Animal Rescue Inc

High Sierra Animal Rescues mission is to save the lives of homeless dogs in the regions served. Our staff and volunteers are dedicated to making our communities better through successful adoptions advancing their welfare and creating human…

Animals
10
Animal Care Sanctuary

Animal care sanctuary's lifesaving mission as a no kill organization envisions a community that promotes turning compassion into action for companion animals by: 1.) adopting healthy pet companions into loving homes. 2.) promoting the…

Animals
11
Spot

SPOT Saving Pets One at a Time is a leading San Diego County all-volunteer rescue organization whose main focus is to save dogs and cats in shelters who are at risk of euthanization and to help other dogs and cats in need as well. In…

Animals
12
Humane Animal Partners

Founded in 2023, humane animal partners is a nonprofit no-kill animal care and adoption center. we are committed to providing for the needs of homeless and owned dogs and cats in our community. we make "friends for life" by connecting…

Animals

For reference, the grantee most central to the portfolio’s shape is Special Operations Warrior Foundation and the most unlike its peers is Friends of Albert Whitted Airport Inc. Resemblance is measured on each organization’s own IRS 990 mission text; it reflects how work is described, not its quality or impact.

For each theme you fund, this compares how the sector’s money is shifting with how your own giving is shifting.

← shrinkinggrowing →↓ leaning in → pulling backsteadyAnimal Rescue and ShelterEnvironmental Conservation …Senior Support ServicesHealth Access Advocacy and …Military Veterans SupportYouth Development ServicesYouth Sports ProgramsCommunity FoundationsIndependent K-12 Schools
the sector your giving your giving is ahead of the sector the sector’s ahead of you· dot size = how much the theme matters to each side
Ordered by the change in your giving — leaning in on top, pulling back at the bottom. The bar between the two dots is how out of step you are with the sector. Hover any row for detail.

Sector change and giving change are each shown relative to their own range, growing (right) or shrinking (left); both normalized, so inflation isn’t mistaken for growth.

Your grantees are a median of 31 years old; the field is 16. You back the established end — and your money leans older still.

THE FIELDby orgYOUR GRANTEESby number22%3%<5yr14%13%5–10yr19%19%10–20yr16%27%20–35yr13%20%35–55yr16%19%55yr+
THE FIELDby orgYOUR MONEYby value22%6%<5yr14%10%5–10yr19%13%10–20yr16%19%20–35yr13%20%35–55yr16%33%55yr+

The field is 22% startups (under 5 years old) — 3% of your grantees by number, and just 6% of your money.

Closures · last 5 years

The orgs you fund almost never close 0.0% lost their exemption, against 13% of the field you don’t fund.

orgs you fund
0.0%0/78
the rest of the field
13%
240,396/1,819,487

Age = years since IRS exemption (a founding proxy). “Closed” = auto-revocation for 3 years of non-filing — a floor on closure, not proof, and bigger established orgs lapse least. Association, not causation.

04the grantee network

70 grantees tracked through their own filings, 2017–2025.

Each one resolved to its own IRS returns and tracked year by year — your grant beside their revenue from every source. Association, dated; never a causal claim.

Counted here: distinct organizations you funded across 20172025, not grant rows in a single year — so this will not match the grant count on the cover. 70 of the 122 grantees resolved in that span have returns of their own we could reconcile; the rest are funded organizations whose filings we could not track year by year.

0
Load-bearing (≥25% of a budget)
14
Early backer (in before they grew)
68/70
Grantees still filing
50/70
Grew since you first funded

Where your money sits — by cause, then by grantee

THE GOOD SAMARITAN CENTER — $90,000 · OtherTHE GOOD SAMARITAN CENTERSERVITE HIGH SCHOOL — $85,000 · OtherSERVITE HIGH SCHOOLST JUDE MEMORIAL FOUNDATION — $67,500 · OtherST JUDE MEMORIAL FOUNDATIONROSARY HIGH SCHOOL — $62,500 · OtherROSARY HIGH SCHOOLBOYS GIRLS CLUB OF FREDERICKSBURG — $49,000 · OtherGILLESPIE COUNTY CHILD SERVICES BOA — $41,000 · OtherFREDERICKSBURG SCHOLARSHIP FUND — $40,000 · OtherSECOND HARVEST FOOD BANK OF SANTA C — $39,000 · OtherST FRANCIS HIGH SCHOOL — $36,500 · Other+73 more — $566,550 · Other+73 moreThe Thacher School Inc — $66,500 · EducationThe Thacher Sc…FREDERICKSBURG ISD EDUCATION FOUNDATION — $48,000 · EducationFREDERICKSBURG…MARINE CORPS-LAW ENFORCEMENT FOUNDA FOUNDATION INC — $18,500 · EducationMARINE CORPS-L…AEROSPACE CENTER FOR EXCELLENCE INC — $16,500 · EducationAEROSPACE CENT…STEPHEN SILLER TUNNEL TO TOWERS FOUNDATION — $15,000 · EducationSTEPHEN SILLER…HILLSDALE COLLEGE — $13,000 · EducationHILLSDALE COLL…RISE UNIVERSITY PREPARATORY — $10,000 · EducationAble Flight Inc — $7,000 · Education+3 more — $11,500 · Education+3 moreBridgeport Fish Enhancement Foundation — $20,000 · AnimalsARCTIC GERMAN SHEPHERD RESCUE INC — $17,000 · AnimalsHUMANE SOCIETY OF PINELLAS INC — $15,500 · AnimalsHOMER ANIMAL FRIENDS — $14,500 · AnimalsSAFE PAWS RESCUE INC — $10,000 · AnimalsALASKA WILDLIFE CONSERVATION CENTER INC — $9,000 · AnimalsThe August Foundation for Alaska Racing Dogs — $7,000 · AnimalsHUMANE SOCIETY OF SEDONA INC — $7,000 · AnimalsALASKA POTBELLY PIG RESCUE INC — $7,000 · AnimalsPENINSULA SPAY NEUTER FUND — $6,500 · Animals+6 more — $14,000 · AnimalsCreate Healthy Management — $51,000 · HealthTHE HEALTH TRUST — $29,000 · HealthANGEL FLIGHT WEST INC — $20,450 · Health+1 more — $2,000 · HealthKIDS IN DISTRESS INC — $20,500 · Human ServicesSoutheastern Guide Dogs Inc — $14,000 · Human ServicesGREY BEARS — $12,000 · Human ServicesTHE GRACE CENTER — $5,000 · Human ServicesHELP A MOTHER OUT — $2,000 · Human ServicesTHE AOPA FOUNDATION INC — $44,500 · Public Safety & DisasterFlorida Sheriffs Youth Ranches Inc — $23,500 · Youth DevelopmentHomer Foundation — $16,500 · Youth DevelopmentWarrior Dog Foundation — $2,000 · Youth Development
Other$1,077,050Education$206,000Animals$127,500Health$102,450Human Services$53,500Public Safety & Disaster$44,500Youth Development$42,000

Each org by its size and your share of it — top-left is where you’re load-bearing

25%50%75%100%$100k$1.0M$10M$100Mgrantee revenue →↑ your share of their budgetThe Thacher School Inc — $66,500 over 4y, 0.0% of budgetCreate Healthy Management — $51,000 over 6y, 0.0% of budgetFREDERICKSBURG ISD EDUCATION FOUNDATION — $48,000 over 7y, 3.3% of budgetTHE AOPA FOUNDATION INC — $44,500 over 9y, 0.1% of budgetTHE HEALTH TRUST — $29,000 over 8y, 0.0% of budgetALASKA MINDFUL PAWS — $27,000 over 5y, 2.1% of budgetVISIONTRUST INTERNATIONAL INC — $25,000 over 6y, 0.1% of budgetFlorida Sheriffs Youth Ranches Inc — $23,500 over 8y, 0.0% of budgetADMIRAL NIMITZ FOUNDATION — $23,000 over 5y, 0.2% of budgetHILL COUNTRY COMMUNITY NEEDS COUNCIL — $22,000 over 5y, 0.7% of budgetKIDS IN DISTRESS INC — $20,500 over 8y, 0.0% of budgetANGEL FLIGHT WEST INC — $20,450 over 9y, 0.0% of budgetBridgeport Fish Enhancement Foundation — $20,000 over 6y, 6.6% of budgetMARINE CORPS-LAW ENFORCEMENT FOUNDA FOUNDATION INC — $18,500 over 7y, 0.1% of budgetFRIENDS OF ALBERT WHITTED AIRPORT INC — $18,000 over 2y, 2.6% of budgetARCTIC GERMAN SHEPHERD RESCUE INC — $17,000 over 4y, 9.4% of budgetAEROSPACE CENTER FOR EXCELLENCE INC — $16,500 over 6y, 0.2% of budgetHomer Foundation — $16,500 over 7y, 0.4% of budgetLIFEMOVES — $16,000 over 4y, 0.0% of budgetHUMANE SOCIETY OF PINELLAS INC — $15,500 over 6y, 0.1% of budgetSTEPHEN SILLER TUNNEL TO TOWERS FOUNDATION — $15,000 over 5y, 0.0% of budgetHOMER ANIMAL FRIENDS — $14,500 over 7y, 1.5% of budgetSoutheastern Guide Dogs Inc — $14,000 over 5y, 0.0% of budgetHILLSDALE COLLEGE — $13,000 over 6y, 0.0% of budgetGREY BEARS — $12,000 over 4y, 0.1% of budgetINTERNATIONAL JUSTICE MISSION — $11,000 over 3y, 0.0% of budgetRISE UNIVERSITY PREPARATORY — $10,000 over 5y, 0.1% of budgetSAFE PAWS RESCUE INC — $10,000 over 3y, 7.2% of budgetTHE JOHN THOMAS DYE SCHOOL — $10,000 over 4y, 0.0% of budgetALASKA WILDLIFE CONSERVATION CENTER INC — $9,000 over 5y, 0.0% of budgetMID-PENINSULA EDUCATION CENTER INC — $9,000 over 3y, 0.1% of budgetAble Flight Inc — $7,000 over 3y, 1.5% of budgetSEMPERVIRENS FUND — $7,000 over 2y, 0.0% of budgetThe August Foundation for Alaska Racing Dogs — $7,000 over 3y, 2.3% of budgetHUMANE SOCIETY OF SEDONA INC — $7,000 over 3y, 0.2% of budgetALASKA POTBELLY PIG RESCUE INC — $7,000 over 5y, 1.0% of budgetPACIFIC CREST TRAIL ASSOCIATION — $7,000 over 3y, 0.1% of budgetDAY WORKER CENTER OF MOUNTAIN VIEW — $6,000 over 3y, 0.4% of budgetLEWIS & CLARK COLLEGE — $6,000 over 2y, 0.0% of budgetSOUTH PENINSULA ATHLETIC AND RECREATIONAL COMMITTEE — $6,000 over 5y, 1.3% of budgetNAVY SEAL FOUNDATION INC — $5,000 over 1y, 0.0% of budgetSPECIAL OPERATIONS WARRIOR FOUNDATION — $4,500 over 2y, 0.0% of budgetYOSEMITE FOUNDATION — $4,000 over 1y, 0.0% of budgetALASKA ZOO — $4,000 over 2y, 0.1% of budgetCAREERS THROUGH CULINARY ARTS PROGRAM DBA CULINARY CAREERS PROGRAM — $3,650 over 2y, 0.1% of budgetTHE MILO FOUNDATION — $3,500 over 1y, 0.3% of budgetSISTERS SERVANTS OF MARY GUILD INC — $2,500 over 1y, 4.4% of budgetALBERT WHITTED AIRPORT PRESERVATION — $2,000 over 1y, 8.1% of budget
Go grantee by grantee — a decade per org, and how each moved after you funded them

A decade per grantee — revenue shaded, your grants as bars, all rows on one timeline.

  • Who funds The Thacher School Inc
  • Who funds Create Healthy Management
  • Who funds FREDERICKSBURG ISD EDUCATION FOUNDATION
  • Who funds THE AOPA FOUNDATION INC
  • Who funds THE HEALTH TRUST
  • Who funds ALASKA MINDFUL PAWS
  • Who funds VISIONTRUST INTERNATIONAL INC
  • Who funds Florida Sheriffs Youth Ranches Inc
  • Who funds ADMIRAL NIMITZ FOUNDATION
  • Who funds HILL COUNTRY COMMUNITY NEEDS COUNCIL
  • Who funds KIDS IN DISTRESS INC
  • Who funds ANGEL FLIGHT WEST INC
  • Who funds Bridgeport Fish Enhancement Foundation
  • Who funds MARINE CORPS-LAW ENFORCEMENT FOUNDA FOUNDATION INC
  • Who funds FRIENDS OF ALBERT WHITTED AIRPORT INC
  • Who funds ARCTIC GERMAN SHEPHERD RESCUE INC
  • Who funds AEROSPACE CENTER FOR EXCELLENCE INC
  • Who funds Homer Foundation
  • Who funds LIFEMOVES
  • Who funds HUMANE SOCIETY OF PINELLAS INC
  • Who funds STEPHEN SILLER TUNNEL TO TOWERS FOUNDATION
  • Who funds HOMER ANIMAL FRIENDS
  • Who funds Southeastern Guide Dogs Inc

The grantmakers whose grantees overlap with yours far more than size alone predicts. Each orbits closer the stronger the alignment; the arcs between them show where they also fund each other. Here it reads as a tightly interlocked camp — most of these funders back each other's grantees too.

The Alaska Community FoundationAK21.1× affinity9 shared granteesties to 8 of 11Hover any node to trace its alignments.Compare side by side →

Open a dossier: The Alaska Community Foundation · Silicon Valley Community Foundation · Gordon E and Betty I Moore Foundation · Rasmuson Foundation · The Community Foundation of the Texas Hill Country Inc · AbbVie Foundation · Shell USA Company Foundation · The David and Lucile Packard Foundation · Jewish Community Foundation of Los Angeles · The Pfizer Foundation Inc · Marin Community Foundation · McKesson Foundation Inc

Affinity is a Gamma-Poisson posterior co-funding rate, re-centered on the typical rate, so thin evidence shrinks toward no signal. A research starting point: overlap is association, not proof of shared intent.

Government reliance of your grantees

Every dot is one organization Helms Foundation Inc funds. Left–right is the share of its income from government; up–down is the share from you. Bigger dots raise more. Filter to federal or a single department — and drag the year to watch it move.

2024
202122232425
no gov · 80%1%3%6%10%your share of their income ↑0%23%45%68%90%share of the org’s income from governmentmedian 0%
  • Lewis & Clark College2% of income from government
  • Southeastern Guide Dogs Inc0% of income from government
  • Kids in Distress Inc0% of income from government
no gov moneyreceives it· size = income
8get no government money at all
14report government grants on their 990 we could not trace to a source (not plotted)
0rely on government for over half their income
⤢ axis zoomed · 0–90%
typical government reliance, FY2025

Government income is each org’s traced federal awards (USASpending — grants and contracts) plus state payments (open checkbooks) as a share of its total revenue (IRS Form 990); the self-reported government-grant line (990 line 1e) is carried for cross-check: a grantee that reports government grants we could not trace to a source is left off the chart rather than shown as receiving none. An association, not a claim that your grant caused the public funding. Coverage is precision-first — a floor, not a census; state records exist for 9 states, so a grantee outside them shows no state figure (dimmed) rather than a false zero. Federal award amounts are obligations, which can span years, so a single-year share is indicative. 990 filings lag 12–24 months.

05Through Plinth

Warm introductions · Powered by PlinthPlus

How do I get to Helms Foundation Inc?

Find your warmest path to Helms Foundation Inc through trustees and officers whose names appear on both boards. Search for your organization and Plinth traces the shortest route it can evidence.

Each link is a name appearing on two organizations’ public IRS 990 filings, matched on that name and, where the filings support it, on location. A same-state match has geographic support, which is a second matching feature rather than confirmation that the two are one person; a cross-state one is the likeliest to be two people who share a name. Every hop shows its tier, low-confidence and distant paths are held back rather than guessed, and it is worth confirming the person before you use the introduction.

On method. Every financial figure here is read directly from IRS e-file XML — your own 990/990-PF and the multi-year returns of the 122 grantees we resolved across every year we hold, several hundred filings in all (a different count from the grant rows on the cover, which are one fiscal year)— each linked to its source. Grantee achievements and outcomes are each organization’s own program-service reporting (Form 990, Part III); we read these as association with sustained funding — the foundation is one of several forces — suppress low-confidence name matches rather than guess, and say so where a figure rests on a single grant or filing. Not everything on this page is a filed figure, and the difference matters. Filed is what you reported on your return. Official is another government record about an organization, such as a federal award or a charity register, joined by name where no shared identifier exists. Resolved is an identity we worked out where the filing named a recipient without an EIN, kept only above a measured confidence threshold. Computed is arithmetic over those, like themes, portfolio clusters and co-funder strength. Context is a statistic about a place rather than about an organization, which is what the need overlay is: it describes the area a grantee’s address sits in, not where its work lands. Inferred is drawn by a model from text, like the partnerships read out of public news and organization websites. Each is labeled where it appears. How we build these →

Generated from your IRS Form 990-PF e-file return for fiscal year 2025, released 2025. Filings run roughly 12–24 months behind; figures are dated accordingly.

Source object · view filing

More from the funding graph