Purple Trading is not a good scalping broker, despite offering zero-spread accounts. The reason being, apart from spreads, they apply hidden price protection gaps, around 3 pips for EUR/USD and up to 7 pips for GBP/USD. Therefore, you can't place limit/stop orders within 3-7 pips from the current price, and stops can't be less than that figure. Even if the stop level value in the MT5 terminal is 0, they don't adhere to it. When scalp trading is not possible, zero spreads are meaningless and only serve to increase commissions.