Hashrate lower on L3+ than what the Antminer shows

I'm averaging 500.64 MH/s on my L3+ on the antminer settings for over a week now, but consistently on Prohashing my MH/S is more like 450-460 sometimes up towards 480's. I want to know why. I have the password field set blank as recommended. I'm earning around $19 average the past few days.

I have the same issue. From what I understand the pool doesn't know your exact speed. What is represented in your local miner status page is what your actual hash speed is.

From the help tab ( back to main site)
Why Hashrate Isn't Everything
It's tempting to look at base hashrate, and arrive at the conclusion that a lower hashrate equals lower payouts. However, the relationship between hashrate and payouts is much more complicated.

Periodically, a coin has a period of low difficulty that increases its profitability to a very high level. The pool will switch some miners to that coin during these intervals. During these periods, base hashrate will appear to be lower than during periods when only litecoins are being mined because work restarts decrease hashrate. However, profitability during these periods is higher, because the blocks being mined are more valuable. Consider the following situation, which arises commonly during mining:

Mine litecoins: Achieve 1 MH/s at 3 cents per MH/s/day = 3 cents per day
Mine casinocoins: Achieve 0.5MH/s at 10 cents per MH/s/day = 5 cents per day
In this instance, it appears at first glance that mining casinocoins is suboptimal because the frequent work restarts lower hashrate. However, the math above demonstrates that the expected value of mining casinocoins is superior to that of mining litecoins, even though the hashrate of mining casinocoins is only half that of mining litecoins.

On cloud mining providers like Nicehash, "negative deltas" and other errors may appear that indicate that some hashrate is being wasted due to work restarts. Prohashing only sends work restarts when doing so would gain more profit even after the restart losses than would continuing to mine the same coin. When using these services, compare actual profitability at several pools to see where you can make the most money, rather than deciding by hashrate alone.

The speed you are seeing on PH is different based on a few factors, the more important of which is the speed at which you actually submit the shares.

If you are having periods of high latency, you will have slower than reported speeds. Also, the diff of the share will increase or decrease your share acceptance rates.