ToolboxLab TestingTotal and Reactive Phosphorus Sediment Test

Labeled water sample bottles packed for certified lab analysis

Lab Testing

Total and Reactive Phosphorus Sediment Test

Name: Total and Reactive Phosphorus Sediment Test
Brand: Lake Pulse
Price: 272.00 USD
Availability: InStock

The entry-level sediment phosphorus number — total stock plus the immediately available slice.

$272

Checkout arrives with the store connection. Orders attach to the lake on your account.

Overview

Two measurements on a lakebed sediment sample: total phosphorus, which is the whole inventory, and orthophosphate as P, the dissolved inorganic form that is immediately available to algae. Orthophosphate by EPA 9056A, MDL 3.3 and RL 4.43 mg/kg; total phosphorus by EPA 6010D, MDL 151.13 and RL 296.35 mg/kg.

Note the reporting limit on total phosphorus. At 296 mg/kg it is roughly 150 times coarser than the 2 mg/kg limit on the Phosphorus Fractionation Sediment Test. Most fine depositional sediment will return a number comfortably above it, but sandy or low-phosphorus sediment can report a non-detect that means "below 296 mg/kg," not "no phosphorus."

This is the screen. Fractionation is the decision tool.

What's measured & how

2 parameters · Sediment phosphorus screen

What's measured & how for Total and Reactive Phosphorus Sediment Test
Parameter	Result type	Unit	MDL	RL	Analytical method
Orthophosphate as P	Quantitative	mg/kg as P	3.3	4.43	EPA 9056A
Total Phosphorus	Quantitative	mg/kg as P	151.13	296.35	EPA 6010D

Orthophosphate as P
Result type:
Quantitative
Unit:
mg/kg as P
MDL:
3.3
RL:
4.43
Analytical method:
EPA 9056A
Total Phosphorus
Result type:
Quantitative
Unit:
mg/kg as P
MDL:
151.13
RL:
296.35
Analytical method:
EPA 6010D

MDL = method detection limit. RL = reporting limit. Provided by the performing laboratory.

You get

Signed laboratory report, filed in your lake's Documents & Reports
Each result loaded into your lake's Data Library (Plus, Lake Admin, PRO)

How it's produced

Test type: Sediment phosphorus screen
Sample: Top 10 cm of lakebed sediment from the deep basin, collected with a corer or dredge you supply (not included)
Return shipping: Prepaid 2-day return to the laboratory
Analyzed by: Independent accredited partner laboratory, with full chain of custody
Method basis: EPA-approved
Turnaround: 10 business days from lab receipt
Analytical method: EPA 6010D; EPA 9056A

Product category

Physical ProductShips to you
ConsumableLab testing

Availability
Kit ships in 2 business days
Shipping
Flat-rate to your front door. Shipping details
SKU
SL-SL-SW-E-S-VT1

Example result

910 mg/kg as P

Method: EPA 6010D

High inventory — fractionation is the next step if the lake stratifies

Turnaround

Results are available within 10 business days of the lab receiving your sample.

What problem does this solve for our lake?

A lake that keeps blooming after the watershed has been addressed usually has a sediment problem, and the first question is simply whether there is an inventory large enough to matter. This test answers that for $272, which makes it the sensible first move before committing $434 to fractionation or six figures to a treatment.
Total phosphorus is the accumulated stock — decades of runoff, stormwater, wastewater, and settled algae. A high number establishes that internal loading is plausible.
Orthophosphate as P is the dissolved, immediately bioavailable fraction. It is the phosphorus that requires no conversion before algae can use it, and it is the fraction released from sediment under low-oxygen conditions.
Where this test stops, stated plainly: two numbers cannot tell you whether an alum treatment will work. The fraction that actually drives seasonal internal loading is redox-sensitive iron-bound phosphorus, and separating it requires sequential extraction. If your total comes back high and your lake stratifies and goes anoxic in late summer, the next step is the Phosphorus Fractionation Sediment Test, not a repeat of this one.
Use this to find out whether there is something to investigate. Use fractionation to decide what to do about it.

What's included?

A complete Total and Reactive Phosphorus Sediment test kit shipped directly to you
All materials required for clean, contamination-free sample collection
Step-by-step collection and preservation instructions
Prepaid 2-day return shipping to our accredited partner laboratory
Analysis by EPA-approved methods at an accredited partner laboratory, with full chain of custody
Results loaded automatically into your lake's account

What's not included

A sediment corer, Ekman dredge, or Ponar dredge. The collection device is NOT included and this test cannot be done with a grab bottle.
Sample collection. You collect the sample; we supply the containers and instructions.
Boat access over the deep basin, which is where the sample needs to come from
Fraction separation. Loosely bound, iron-bound, aluminum-bound, and biogenic phosphorus require the Phosphorus Fractionation Sediment Test.
A measured release rate or phosphorus flux
Water column phosphorus, which is a separate test on a separate sample
Sediment metals or organic contaminants
An alum dose calculation or dredging volume estimate

Requirements

A SEDIMENT sample, not a water sample. This test requires a core or a dredge grab from the lakebed. A grab bottle of water will not produce a usable sample and the kit does not include a collection device.
A sediment corer or an Ekman or Ponar dredge, which you supply or borrow. A corer preserves the vertical layering; a dredge does not. Record which you used — it changes how the result should be read.
A sample from the depositional zone, meaning the deepest basin where fine material settles, not the shoreline and not sand or gravel
The top 10 cm of sediment, which is the biologically and chemically active layer
The jar filled with minimal headspace and minimal air exposure
Kept cold and dark, shipped the same day
Depth and coordinates recorded, so the site can be reoccupied in future years
A Plus, Lake Admin, or PRO subscription to have results loaded into your Lake Pulse account
Questions about site selection, timing, or which test fits your lake? Contact the Lake Pulse Boathouse before you order.

What you get back

Results

Total phosphorus and orthophosphate as P, reported in mg/kg with detection and reporting limits
A baseline sediment inventory, and a defensible answer to whether internal loading is worth investigating further
A clear escalation path — a high total on a stratifying lake points directly at fractionation as the next step
Results load automatically into your lake's Data Library in the Lake Pulse Portal
Data can be charted in the Analytics Hub, used to trigger alerts, or shared with your board and members
A downloadable, signed lab report is filed in your lake's Documents & Reports for permanent reference
Results are found in your lake's portal, accessible only to Plus, Lake Admin, and PRO subscription tiers

Pro tips

Read the reporting limit before you read the result. A non-detect on total phosphorus means below roughly 296 mg/kg. On a sandy lake that is a real possibility and it is not the same as a clean sediment.
Sample the deep basin, top 10 cm, and record both. Sediment phosphorus varies by an order of magnitude between a shoreline and a depositional zone.
If the total is high and your lake stratifies, go straight to fractionation. Repeating this test will not tell you anything new, and fractionation is what an engineer will ask for.
Same site, same depth, same device each time. Sediment sampling is less repeatable than water sampling, so the discipline matters more.
Results are dry-weight. Two samples of different water content are not directly comparable, which is one reason the fractionation test reports percent water and this one does not.
This is the cheap way into the sediment question. For a subscriber unsure whether internal loading is even relevant, $272 is the right size of bet.

Results sync to the Portal for Plus, Lake Admin, and PRO subscribers

Results from this product land in your lake's shared record in the Portal — next to everything else your lake has ever measured, instead of in an inbox.

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About these results

Every result shows the date and time the sample was collected. Results reflect one sample, collected at a specific place and depth, and analyzed by an independent accredited laboratory using the method listed on this page. Lake conditions change across a lake and over time, sometimes within hours, in ways a single sample may not capture. Every method has detection and reporting limits; where the laboratory provides them, they are reported with your results. A detection is not a diagnosis, and a non-detection does not prove absence. Results are not a regulatory or compliance determination unless the agency involved accepts them as one. Results can help you make decisions about safe swimming and water use, but no result is definitive for every place and time. It is always good practice to check posted signs and your state or local health authorities. Recommendations are options to consider; decisions, and responsibility for any action taken, rest with you.

Sediment results describe the sampled location and depth interval only. Sediment varies considerably across a lakebed.

Questions on this?

Our team can help you choose the right solution for your lake, explain how results sync to your Portal, or point you to the right subscription.

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